Question

read the sentence.
open his chemistry book, trevor knew he had a long night of studying ahead of him.
which is the best replacement for the underlined word?
to open
opening
opened
opens

Explanation:

The sentence needs a participle to introduce the action. "Opening" is the present participle form which shows an ongoing action simultaneous with "knew". "To open" (infinitive) implies purpose which doesn't fit. "Opened" (past participle) would imply a passive action (book being opened by someone else) which is wrong here as Trevor is the one opening. "Opens" (simple present) is incorrect for the context of the sentence structure.

Answer:

Opening