Select the most appropriate word to fill in the blank.

If you ______ your book, I'd like to borrow it.

have finished

The most appropriate word to fill in the blank is have finished.

The sentence is in the present tense, but it is talking about something that has not happened yet. The verb "have finished" is the past participle of the verb "finish," and it is used to talk about something that happened in the past but has a bearing on the present. In this sentence, the speaker is asking the listener to borrow their book after they have finished reading it.

The other options are not as appropriate.

• The verb "will finish" is used to talk about something that will happen in the future. It is not clear how the speaker knows that the listener will finish their book in the future.
• The verb "finish" is the simple present tense of the verb "finish," and it is used to talk about something that is happening now or that happens regularly. It is not clear how the speaker knows that the listener is finishing their book now.
• The verb "finished" is the past tense of the verb "finish," and it is used to talk about something that happened in the past. It is not clear how the speaker knows that the listener finished their book in the past.