In Pair A sentence 1, to eat is infinitive, while drinking has an -ing ending and is present participle. In contrast, each of the first sentences do not have parallel structure. (See Rule 6 in my post on using “the” in English. Finally, in sentence C2, we see both nouns in the singular with “the” used to label the nouns and broad categories. In sentence 2 of Pair B, took and went also show parallel structure both are past tense verbs. So the grammar structures of these verbs are the same - the structures are parallel. In Pair A sentence 2, to eat and to drink are both infinitive verb forms. Each #2 sentence has matching pairs of verbs or nouns. The second sentence is the one with parallel structure.

In each of the sentence pairs above, the second sentence is the better one. Like I said, this is an advanced English concept. But if you’re still not sure, don’t feel bad. You may have already sensed the “good” sentence in each of the pairs above.

The raccoon and skunk are animals found primarily in North America.

The raccoon and skunks are animals found primarily in North America.

I am taking the bus and went to school.

I like to eat apples and to drink apple juice too.

I like to eat apples and drinking apple juice too.

So before we go into the exact definition of parallel structure, let me show you some sample sentences. But examples of good and bad parallel structure can be surprisingly obvious. Parallel structure is a fairly advanced grammar concept.

Understanding parallel structure in English can help your TOEFL score. Parallel structure in English refers to the use of similar grammar constructions within a sentence or clause.

Parallel structure definition