Question

in which sentence are the words in bold an infinitive?
o we were forced to remain at the library because mom had a flat tire.
o our remaining at the library meant we would miss soccer practice.
o we remained at the library because mom couldnt get there by 2 oclock.
o we felt that remaining at the library was a waste of time.

Explanation:

An infinitive is the base - form of a verb preceded by 'to'. In the first sentence, "to remain" is an infinitive. In the other sentences, "remaining" is a gerund (a verb form that functions as a noun).

Answer:

We were forced to remain at the library because Mom had a flat tire.