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Writing Grammatically Correct Sentences

Grammar is the study of how words can be combined into sentences to make meaning. Why does it matter if you can write grammatically correct sentences? One reason is that many grammar conventions are functional. If you write, “After sitting on a mildewed shelf in the garage for thirty years, my brother decided to throw out the old computer,” you’ve said that your brother spent thirty years sitting on a mildewed shelf in the garage, which gave him plenty of time to decide what to do with the old computer. If you write, “Did Sean tell Liam when he was expected to report to work?” the reader might have a hard time figuring out whether he refers to Sean or Liam.

Even if a grammar mistake doesn’t make you sound silly or confuse the reader, it can hurt you by making readers doubt your credibility. The logic is that if you are careless about grammar, you might also be careless about the quality of the technical information you communicate. Many readers will assume that documents that are unprofessional because of grammar problems might also be unprofessional in other ways.

This section will review nine principles for using clear, correct grammar:

A sentence fragment is an incomplete sentence. A sentence fragment occurs when a sentence is missing either a verb or an independent clause. To correct a sentence fragment, use one of the following two strategies:

1. Introduce a verb.

2. Link the fragment (a dependent element) to an independent clause.

A comma splice is an error that occurs when two independent clauses are joined, or spliced together, by a comma. Independent clauses in a comma splice can be linked correctly in three ways:

1. Use a comma and a coordinating conjunction (and, or, nor, but, for, so, or yet).

2. Use a semicolon.

3. Use a period or another form of terminal punctuation.

In a run-on sentence (sometimes called a fused sentence), two independent clauses appear together with no punctuation between them. A run-on sentence can be corrected in the same three ways as a comma splice:

1. Use a comma and a coordinating conjunction (and, or, nor, but, for, so, or yet).

2. Use a semicolon.

3. Use a period or another form of terminal punctuation.

Pronouns must refer clearly to their antecedents—the words or phrases they replace. To correct ambiguous pronoun references, use one of these four strategies:

1. Clarify the pronoun’s antecedent.

2. Clarify the relative pronoun, such as which, introducing a dependent clause.

3. Clarify the subordinating conjunction, such as where, introducing a dependent clause.

4. Clarify the ambiguous pronoun that begins a sentence.

If you begin a sentence with a demonstrative pronoun that might be unclear to the reader, be sure to follow it immediately with a noun that clarifies the reference.

When comparing or contrasting items, make sure your sentence communicates their relationship clearly. A simple comparison between two items usually causes no problems: “The X3000 has more storage than the X2500.” Simple comparisons, however, can sometimes result in ambiguous statements:

If you are introducing three items, make sure the reader can tell which two are being compared:

Beware of comparisons in which different aspects of the two items are compared:

In general, adjectives are placed before the nouns that they modify: the plastic washer. In technical communication, however, writers often need to use clusters of adjectives. To prevent confusion in technical communication, follow two guidelines:

1. Use commas to separate coordinate adjectives. Adjectives that describe different aspects of the same noun are known as coordinate adjectives.

portable, programmable device

adjustable, removable housings

The comma is used instead of the word and.

Sometimes an adjective is considered part of the noun it describes: electric drill. When one adjective modifies electric drill, no comma is required: a reversible electric drill. The addition of two or more adjectives, however, creates the traditional coordinate construction: a two-speed, reversible electric drill.

2. Use hyphens to link compound adjectives. A compound adjective is made up of two or more words. Use hyphens to link these elements when compound adjectives precede nouns.

a variable-angle accessory

increased cost-of-living raises

The hyphens in the second example prevent increased from being read as an adjective modifying cost.

A long string of compound adjectives can be confusing even if you use hyphens appropriately. To ensure clarity, turn the adjectives into a clause or a phrase following the noun.

The subject and verb of a sentence must agree in number, even when a prepositional phrase comes between them. The object of the preposition might be plural in a singular sentence.

The object of the preposition might be singular in a plural sentence.

Don’t be misled by the fact that the object of the preposition and the verb don’t sound natural together, as in tests is or test are. Here, the noun test(s) precedes the verb, but it is not the subject of the verb. As long as the subject and verb agree, the sentence is correct.

A pronoun and its antecedent (the word or phrase being replaced by the pronoun) must agree in number. Often an error occurs when the antecedent is a collective noun—one that can be interpreted as either singular or plural, depending on its usage.

When the individual members of a collective noun are emphasized, however, a plural pronoun is appropriate.

Two verb tenses are commonly used in technical communication: the present tense and the past perfect tense. It is important to understand the specific purpose of each.

1. The present tense is used to describe scientific principles and recurring events.

When the date of the argument is omitted, some writers express the entire sentence in the present tense.

2. The past perfect tense is used to describe the earlier of two events that occurred in the past.