Adjective-Adverb Errors

It is sometimes easy to use an adjective as an adverb and vice versa. To avoid this kind of error, keep in mind what adjectives and adverbs do. Adjectives only modify nouns and pronouns. Adverbs modify verbs, adjectives, and other adverbs. When you are writing, consider what it is you are attempting to modify and then select the appropriate modifier.

When using comparative adjectives and adverbs, be careful to select their correct form. When you are comparing two elements, use the comparative ending (usually -er). When comparing three or more elements, use the superlative ending (usually -est). Keep in mind that there are some adjectives and adverbs that have nonstandard endings. Consult your dictionary if you are in doubt.

Never use a double superlative or comparative. Example:

That was the most stupidest book that I've ever read. [to write this correctly, delete "most"]

Apostrophe Misuse

Apostrophes have three basic uses:

  • To show possession
  • To mark the omissions in contractions
  • To form certain plurals

Apostrophes may be used to show possession. For singular nouns, acronyms, and indefinte pronouns, add the apostrophe and "s":

  • Einstein's law
  • someone's book
  • GDW's new game system

For plural nouns that end in "s", simply add an apostrophe:

  • the students' grades
  • the teachers' pay

For compound nouns and phrases that indicate joint ownership, add an apostrophe and "s" to the last word:

  • Steve and Jim's dorm room
  • Percy Bysshe Shelley's poem
  • My brother-in-law's design

For individual ownership, use the apostrophe and "s" with both names:

  • Coleridge's and Wordsworth's poems
  • Steve's and Jim's dorm rooms

Apostrophes are used to indicate omissions in contractions and dates:

  • can't [can not]
  • '90 [1990]
  • who'll [who will]
  • who's [who is]

Do not use apostrophes with personal pronouns to show possession. Personal pronouns use the possessive case to show possession. "Its" is often misused this way. "Its" is the possessive case for "It" and does not require an apostrophe.

Article Errors

Indefinite articles are generally used before nouns that are nonspecific, singular, and countable (individual items that you can count and cannot view as a mass). The indefinite articles are "a" and "an". Use "a" before consonant sounds and use "an" before vowel sounds.

  • a lab report
  • a microscope
  • a three-variable map
  • a binary parallel adder

Definite articles, such as "the" are used before specific nouns-nouns that are not countable. They may be either singular or plural.

  • the computer on my desk
  • the Heisenberg uncertainty principle
  • the law of non-contradiction
  • the reference points in a coordinate system

Sometimes it is okay to omit articles. Here are some of those situations:

  • before a noncount noun [Let's buy furniture]
  • before plural countable nouns that do not refer to a specific item [read books]
  • before a plural noun that has a general meaning [John wants passing grades]
  • in certain common expressions [go to class]

Awkward Phrasing or Idiom

An idiom is a group of words whose meaning is different from the individual meanings of the words in the group. Examples would be such things as "eating crow", "raining cats and dogs, and "on the go". It is easy to use idiomatic expressions incorrectly. The correct preposition to make a phrase idiomatic is not always apparent. For example: "comply to" as opposed to "comply with" (idiomatic). Hence, choosing the incorrect words for an idiomatic expression can lead to awkward phrasing. If you are unsure about the use of an idiomatic expression, consult your dictionary.

Some common idioms:

  • all the same
  • to mean well
  • turning something over in one's mind
  • hang up
  • hang out
  • get even with
  • get out of hand
  • on the spot
  • wait on
  • differ from
  • get along
  • move on

Capitalization Errors

Here's a list of the types of words that require capitals:

  • Names of persons (including nicknames)
  • Names of things
  • Trademarks
  • Names of peoples
  • Names of languages
  • Geographical names
  • Names of organizations
  • Names of institutions
  • Names of government agencies
  • Names of companies
  • Days of the week
  • months
  • Holidays
  • Historical documents
  • Historical events
  • Historical periods or eras
  • Religions
  • The believers of a religion
  • Holy books
  • Holy days
  • Any word denoting a supreme being
  • Personifications
  • Words derived from proper names
  • Acronyms
  • Titles of persons when they precede the name
  • Major words in the titles of books, plays, essays, etc.
  • The pronoun "I" and the interjection "O"
  • First word of a sentence
  • First word of directly quoted speech

Comma Omissions

Sometimes it is difficult to know exactly when you need a comma and when you do not. Below, I'll summarize instances in which a comma is required.

  • When an independent clause is linked together with a coordinating conjunction, a comma must be placed before the conjunction.
    Example: A circuit with ten states, using one discrete voltage value for each state, can be designed, but it would posess a very low reliability of operation. [the coordinating conjunction "but" links two independent clauses together. Hence, a comma is placed before "but."]
  • Commas must follow introductory phrases.
    Examples: For each instruction, the control unit informs the processor to execute the operation specified by the instruction. [a comma must follow the introductory prepositional phrase, "for each instruction."]

    Furthermore, one of the most powerful ways of analyzing data is to display them as a graph. [a comma must follow the introductory word "furthermore."]

  • Commas must follow adverb clauses when they come before independent clauses.
    Examples: When two sounds heard together are unpleasant, they create dissonance. ["When two sounds heard together are unpleasant" is an introductory adverb clause and must be followed by a comma]

    As radon decays, it produces gaseous radon.

  • Commas must be used to separate items in a series.
    Example: The memory unit stores programs as well as input, output, and intermediate data.
  • Commas must be used to set off nonrestrictive elements, parenthetical elements, and contrasted elements.
    Nonrestrictive elements are phrases that do not provide essential information about any noun or pronoun in a given sentence. Such phrases are completely set off by commas.

    Example: The ratio of the square of the periods of any two planets, according to Kepler, is equal to the ratio of the cube of their distances to the sun. [The phrase, "according to Kepler", is nonrestictive and must have a comma before and after it]

    Example, contrasted elements: Fuel reprocessing technology, unlike nuclear waste production, has not advanced.

    Example, parenthetical elements: Light pollution, or "sky glow", seriously diminishes the amount of starlight visible to the naked eye.

Comma Splice

If you have two main clauses in a sentence connected by a comma rather than a conjuction, you have a comma splice.

Here's an example:

When a processor is combined with a control unit, it forms a component called a CPU, a CPU contained in a small integrated circuit package is known as a microprocessor.

Here you have two main clauses (a phrase containing a subject and a predicate that can stand alone as a sentence) connected by a comma. There are three simple ways to correct a comma splice:

  • Drop the comma and form the main clauses into two separate sentences:
    When a processor is combined with a control unit, it forms a component called a CPU. A CPU contained in a small integrated circuit package is known as a microprocessor.
  • Place a coordianting conjunction immediately after the comma:
    When a processor is combined with a control unit, it forms a component called a CPU, and a CPU contained in a small integrated circuit package is known as a microprocessor.
  • Replace the comma with a semicolon:
    When a processor is combined with a control unit, it forms a component called a CPU; a CPU contained in a small integrated circuit package is known as a microprocessor.


Contractions are considered inappropriate for formal writing. So, do not use them in thesis papers, lab reports, term papers, or anything academic submitted for publication.

Double Negatives

In formal written English, you should never use two negative expresions to express a single negation. When you do, it is referred to as a "double negative." To correct a double negative, simply delete one of the negatives and add any other necessary words.

Examples: Jeff did not do no lab report. [Delete "no" and add an article before "lab". Correct: Jeff did not do a lab report.]

Jeff thought the instructor would not say nothing to him about it. [Simply delete "not". Correct: Jeff thought the instructor would say nothing to him about it.]

Also, you should keep in mind that words such as scarely, hardly, and barely are considered to be negatives. Hence, do not use them with other negatives: "not hardly", "without scarcely", etc.

Failure to Use A Possessive Before a Gerund

A gerund is a verbal (verb used as a noun, adjective, or adverb) that ends in "-ing" and functions as a noun within a sentence. Whenever a pronoun comes before a gerund, it uses the possessive form.

Example: The instructor did not approve of him assisting Don with his lab report. [the pronoun "him", as it comes before the gerund "assisting", must take the possessive form "his"]

Faulty Coordination

When writing, you should always pay close atention to the logic of your sentence construction. Always make sure that your subject and predicate logically work together.

Example: I read an article in the paper that believes in capital punishment. [articles do not believe, people do]

Rewite it thus: The author of an article I read in the paper believes in capital punishment.


A fragment is a group of words that begins with a capitalized word and ends with a period, yet it does not form a complete sentence. For a group of words to be considered a sentence, it must have both a subject and a verb. Lacking either, the group of words in question is a fragment. Fragments are usually either some kind of verbal phrase or a subordinate clause punctuated as a sentence.

Here's an example: To understand the operation of each digital module. It is necessary to have a basic knowledge of digital systems and their general behaviour.

The first group of words is merely a verbal phrase. It contains neither a subject nor a verb. To correct it, you must either connect the phrase to another sentence or supply the missing parts:

To understand the operation of each digital module, it is necessary to have a basic knowledge of digital systems and their general behavior.

Keep in mind that sometimes writers use fragments on purpose in order to provide emphasis. However, in formal writing, you should never use fragments unless you have a very good reason.

Fused Sentence

A fused sentence is what usually happens when one attempts to correct a comma splice by simply omitting the comma. It is two main clauses jammed together without the use of connecting punctuation or conjunctions.

An example: Binary logic is used to describe the manipulation and processing of binary information it is particularly suited for the analysis and design of digital systems.

There are two main clauses in the example above that must be connected by either proper punctuation or the use of a coordinating conjuction. Here are a couple of ways this sentence can be corrected:

Binary logic is used to describe the manipulation and processing of binary information. It is particularly suited for the analysis and design of digital systems. [divide it at the fused point and form two separate sentences]

Or: Binary logic is used to describe the manipulation and processing of binary information, and it is particularly suited for the analysis and design of digital systems. [a comma and a conjunction inserted at the fused point]

A fused sentence is sometimes called a "run-on sentence".

Dangling Modifiers

A dangling modifier is a word or group of words within a sentence that does not clearly relate or refer to any other part of the sentence. The usual method for correcting dangling modifiers is to supply words or to rearrange the words of the sentence to make the meaning clear.

Here's an example: Using an ammeter, the electrical current was measured.

In this example, there is no clear reference for the phrase, "using an ammeter". The "electrical current" doesn't use the ammeter and the ammeter wasn't "measured". Hence, a word must be supplied. From the sentence, we can infer that a person used an ammeter to measure electrical current. Thus, supplying a subject will correct the sentence:

Using an ammeter, he measured the electrical current.

Here, "using an ammeter" clearly refers to "he".

Misused Semicolons

Semicolons are used for two purposes: (1) to link independent clauses, and (2) to separate sentence elements that already contain commas.

Independent clauses that concern related subject matter can be linked in three ways:

  • a semicolon
  • a coordinating conjunction
  • punctuated as seperate sentences

How closely the independent clauses are related determines which of the above methods you should use. If it's a very strong connection, use a semicolon. If the connection is weaker, use a coordinating conjunction. If the connection is very weak or if you want to separate the ideas, punctuate them as separate sentences.

Semicolons are misused when one tries to connect sentence parts of different grammatical structure. You cannot use a semicolon to connect a clause with a phrase or an independent clause with a dependent clause.

Mixed Construction

Mixed construction refers to a sentence that is somewhat confusing due to a switch between two different types of grammatical patterns.

An example: If a person intends to pass the exam, then you should start tonight.
This example shows a shift from third person to second person. To avoid committing mixed construction errors, focus on consistency. If you use first person in the first clause of a sentence, then use it the second or any other clauses in the sentence. Other examples would involve shifts in verb tense, tone, or even style (slang vs. formal diction).


Words or ideas in a sentence that are parallel in meaning must be parallel in structure as well.

Some examples: Seeing is to believe. [to make this sentence parallel, rewrite it thus: "Seeing is believing"]

Jim likes to surf the net, to design games, and watching science-fiction movies. [the items in the series should all have the same grammatical structure. Hence, rewrite the third item as "to watch science-fiction movies"]

Past Tense Errors

Always be careful to add "-d" or "-ed" to a word to form the past tense unless it is an irregular verb such as lay, lead, pay, study, etc. If you are unsure what the past tense form of a verb is, consult your dictionary. These types of errors are most commonly committed with verbs in which the "-d" or "-ed" is not emphasized when the word is spoken. This includes such words as "ask/asked", "suppose to/supposed to", and "use to/used to".

Example: I am suppose to turn my paper in today. [write "supposed" rather than "suppose"]

Plurality Errors-Nouns

Although the plurals of most nouns are formed by simply adding "s" to the singular form, there are some nouns that are nonstandard. Here's a brief summary:

  • Some nouns end in "f" or "fe" such as "thief" or "roof". For most of these, change the "f" to "ve" and then add "s". [thief-thieves] However, there are some nouns like "roof" where this is not done. [roof/roofs]
  • Some nouns end in a consonant + "y" [party] For these nouns, replace "y" with "i" and add "es" [parties]
  • Some nouns end in a consonant + "o" [hero] Usually for these nouns you simply add "es" [heroes]. There are some, however, like "pro", where you add only "s" [pros]
  • Some nouns are irregular and take a completely different form for the plural: goose/geese, datum/data/locus/loci.

If you are unsure how to form the plural of a noun, consult your dictionary.

Pronoun Case Errors

The case of a pronoun indicates the relation of the pronoun to other parts in a sentence. There are three basic pronoun cases: subjective, possessive, and objective. The pronoun form also changes from singular to plural. Consider:

  • Subjective singular: I
  • Possessive singular: my or mine
  • Objective singular: me
  • Subjective plural: we
  • Possessive plural: our or ours
  • Objective plural: us

Here are some rules to follow that will assist you in choosing the correct case for a pronoun:

  • For the subject of a verb and the subject complement, always use the subjective case.
  • For the object of a verb, verbal, infinitive, or preposition, always use the objective case.
  • Always use the possessive case before a gerund.
  • Use "who" or "whomever" for the subject of a clause.
  • Use "whom" for all objects.
  • Make sure all pronouns agree in number and gender with what they refer to.

Pronoun Errors-Ambiguous

Pronouns should clearly refer to a noun preceding them in a sentence. Sometimes, depending on how a sentence is written, a pronoun could seem to refer to more than one noun.

Example: Jeff told John that his answer to the problem was incorrect.

In this sentence it is unclear whether "his" refers to "Jeff" or "John". To write the sentence correctly, you must determine what the meaning of the sentence is and then rewrite it to clearly express your chosen meaning. The example above could be rewritten in one of two ways:

  • Jeff told John, "Your answer to the problem is incorrect."
  • Jeff told John, "My answer to the problem is incorrect."

Pronoun Reference

Whenever a pronoun is used, it must clearly refer to its antecedent (the word for which it stands). Sometimes a sentence can be worded in such a way that a pronoun could have two or more possible antecedents or the antecedent could be so far removed from its pronoun that it is difficult to determine exactly what word the antecedent is. Sometimes a sentence may contain a pronoun that does not even have an antecedent. In all cases, the sentence must be rewritten so that all pronouns clearly refer to the word for which they stand. Usually, the antecedent should immediately precede its pronoun.

Here's an example: Newton's law of universal gravitation states that the force between them depends on the product of their massess divided by the square of the distance betwen their centers.

What does "them" and "their" in this sentence refer to? They have no antecedent, hence, the pronoun "them" must be replaced with the word or words for which it stands. In this case, it is "two planets".

Shifts in Person or Number

When writing, you must be careful not to make abrupt shifts in person or number. Such shifts can be quite disconcerting for the reader. If you use the singular form of a word in a sentence, you must use it for any other ocurrences of the word within the sentence. You must show the same consistency with person (first, second, third). If you use first person in a sentence, you must continue to use first person.

Consider: The senior design team expects to get an "A" on their project.

This is incorrect because "team" is singular and "their" is plural. To correct it, write the sentence in one of the following ways, depending on what you want the sentence to mean:

  • The senior design teams expect to get an "A" on their projects.
  • The senior design team expects to get an "A" on its project.

Shifts in Tense

The form of a verb changes when it expresses "when" something happened: the past, present, or future. The form of the verb is called its "tense". There are six tenses in the English language: simple past, simple present, simple future, past perfect, present perfect, and future perfect. Simple tenses refer only to the time in which an action ocurred. Perfect tenses refer to the time in which an action ocurred and the time in which the action will be completed. In general, it is considered incorrect to shift tenses within a sentence, paragraph, or complete written project without a very good reason.

Consider the following: Tom went to the game, but he leaves early. [The shift in tense makes this sentence sound quite awkward. Replace "leaves" with "left" and the sentence will read correctly.]

Subject-Verb Agreement

When writing a sentence, the subject must always match the verb in number. A plural subject requires a plural verb and a singular subject requires a singular verb.

For many verbs, the singular form has an -s at the end or requires that you drop a -y and add -ies. [Bill writes, Joe talks, Jane studies, etc.]

Plural subjects simply require the regular present tense form of the verb. [Jon and Bill write, The students read, Joe and Jane talk, etc.]

An Example: The books on the shelf is about electrical engineering.

In this example, the subject, "books", is plural and the verb, "is", is in a singular form. To make the subject and the verb agree, change one to match the other, depending on your intent:

  • The book on the shelf is about electrical engineering. (The subject and verb are both singular)
  • The books on the shelf are about electrical engineering. (The subject and verb are both plural)

Keep in mind that you only need to worry about agreement with present tense verbs.

Problems with subject-verb agreement are not always as simple as the example above. Sometimes errors result from failure to correctly identify the subject's number due to some of the following reasons:

  • Other words or phases found between the subject and the verb, such as a prepositional phrase, can obscure the identity of the subject. For example: "The bending of waves around an object in their path is known as diffraction". Is the subject "bending", "waves", "object", or "path"? In this case, the subject is "bending". All of the others are objects of prepositions.
  • Generally, compound subjects are plural. However, compound subjects that refer to a single person, place, or thing require a singular verb. For example: "The founder and director of the institute is Paul Johnson." In this example, both "founder" and "director" refer to the same person.
  • Collective nouns, such as committee, herd, etc., are considered singular even though such nouns stand for a plurality of things.

Unnecessary Commas

When commas are unnecessarily placed in sentences, it can lead to confusion and misinterpretation. To avoid misplacing commas, heed the following rules:

  • Never use a comma to separate a subject from its verb or a verb from its object.
    Example: A combinational circuit, may have don't-care conditions. [the comma separates "circuit" from its verb, "may have"]
  • Do not place commas after coordinating conjunctions.
    Example: A flip-flop can store one bit of information and, it has two outputs. [the comma is unnecessary]
  • Do not use commas to set off necessary clauses.
    A satellite, in a circular orbit, accelerates toward Earth at a rate equal to the acceleration of gravity at its orbital radius.[the phrase "in a circular orbit" is restrictive. That is, it limits the word it modifies (satellite). For such phrases, commas are not needed]
  • When placing commas in a series, do not place them before the first item or after the last item.
    Example: The slightest, push, pull, or twist, could accelerate the huge satellite, giving it an incorrect or even dangerous velocity. [the commas before "push" and after "twist" are unnecessary]

Verb Errors (wrong form)

There are three basic forms or principle parts of a verb: the past, the simple present, and the past participle. Sometimes the present participle is includeed as well. The present consists of the verb or the verb plus a helping verb (run, is running, can run). The past form is generally formed by adding -d or -ed and can also be used in conjunction with helping verbs (walk: walked, might have walked). Many verbs, however, have nonstandard forms. They are known as irregular verbs and they tend to be quite troublesome when one attempts to identify their principle parts. If you are unsure about the principle parts of a verb, consult your dictionary. Below is a list of some of the more troublesome verbs. Their forms are listed in this order: present, past, past participle, and present participle.

  • lay, laid, laid, laying
  • lie, lay, lain, lying
  • set, set, set, setting
  • sit, sat, sat, sitting
  • pay, paid, paid, paying
  • go, went, gone, going
  • fall, fell, fallen, falling
  • choose, chose, chosen, choosing
  • burst, burst, burst, bursting
  • loosen. loosened, loosened, loosening
  • rise, rose, risen, rising
  • run, ran, run, running
  • grow, grew, grown, growing
  • stink, stank, stunk, stinking

Keep the following in mind: if the subject causes the action, use a helping verb and the present participle. If the subject is affected by the action, use a helping verb and the past participle.