Question

Which sentence has a nonparallel structure?
They need to think further about the problem and to learn more about the context.
He suggests that they think further about the problem and learn more about the context.
She expects them to think further about the problem and learning more about the context.
I can only suggest thinking further about the problem and learning more about the context.

Answer 1

One tell tale way to know if a sentence has parallel structure is identifying gerunds.

Answer 2

Gerunds are words that end in ing

Answer 3

Do you see any of the options that have words like this?