Students learn not only what the rules of parallel structure are, but also how to use paired joining terms.

Parallel structure is important in English, but it is all too often used incorrectly. From simple words to complex phrases, the basic rule of parallel structure is that all the elements must be equal (i.e., they must match) on either side of the comma or conjunction. Parallel structure is especially important when it comes to paired joining terms such as not only...but also, either...or, neither...nor, and both...and. Listed below are some of the rules, examples, and tricky cases that you can use when teaching your students about these terms.

General Rules of Parallel Structure

There must be a match in form and function when joining words, phrases, clauses, or sentences in English. The form must be the same; i.e., nouns must be joined to other nouns, verb + object phrases must be joined to other verb + object phrases, SVO clauses must be joined to other SVO clauses, etc.

Examples:

• She cleaned the kitchen, the bathroom, and dusted the living room. (wrong: N, N, V + N)
• She cleaned the kitchen, the bathroom, and the living room. (correct: N, N, N)
• I wrote the report, called the client, and the storeroom was organized. (wrong: V + N, V+ N, N + V)
• I wrote the report, called the client, and organized the storeroom. (correct: V + N, V + N, V + N)

The grammatical function must also be the same; i.e., adjectives must be joined to other adjectives, past verbs should be joined to other past verbs, gerunds must be joined to other gerunds, etc.

Examples:

• The house was old but a beauty. (wrong: Adj, N)
• The house was old but beautiful. (correct: Adj, Adj)

Specific Cases of Parallel Structure: Paired Joining Terms

The following expressions are mainly used for emphasis. They are especially common in writing. The most important thing to remember about these expressions is that the first joining term must be placed before the part of the sentence that has the same form and function as the second part of the sentence that you’re trying to match. It’s tricky! Native speakers and students alike make mistakes with this. Showing your students the examples below should make it clear.

1. Not only...but also

• We not only ate pizza, but also pasta. (wrong: V + N, N)
• We ate not only pizza, but also pasta. (correct: N, N)

Be careful! When joining two sentences (using not only at the beginning of the sentence), the subject and verb become inverted.

• Not only she will take a test, but she will also give a presentation. (wrong: no inversion)
• Not only will she take a test, but she will also give a presentation. (correct: inversion)

For practice with not only...but also, try the exercise in ESL Library’s Chris Hadfield lesson.

2. Either...or

• The students can either choose to study or to exercise. (wrong: V + Infinitive, Infinitive)
• The students can choose either to study or to exercise. (correct: Infinitive, Infinitive)

3. Neither...nor

• My roommate neither likes the red dress nor the green dress. (wrong: V + N, N)
• My roommate likes neither the red dress nor the green dress. (correct: N, N)

Point out to students that using not with either...or has the same meaning as neither...nor. Neither...nor is quite formal and not often used in speaking, so understanding how to change it to not with either...or is useful for students.

• They ate neither the apples nor the oranges. (correct, but formal, used in formal writing)
• They didn’t eat either the apples or the oranges. (correct, more common in informal writing and speaking)
• They didn’t eat the apples or the oranges. (correct, the most common in speaking)

4. Both...and

• The child both wanted to ride the roller coaster and ice cream. (wrong: V + Infinitive + N, N)
• The child wanted both to ride the roller coaster and ice cream. (wrong: Infinitive + N, N)
• The child wanted both to ride the roller coaster and to eat ice cream. (correct: Infinitive + N, Infinitive + N)

I hope you found this post useful for both your students and yourself,

Tanya

Source: The Chicago Manual of Style, 16th edition, section 5.214.