Behind the stage (is, are) a large area for instruments.

Few (knows, know) the results yet.
All of the listeners (waits, wait) anxiously
Most of the day (was, were) very entertaining.

Behind the stage is a large area for instruments.

Few know the results yet.
All of the listeners wait anxiously.
Most of the day was very entertaining.

Behind the stage is a large area for instruments.

Few know the results yet.
All of the listeners wait anxiously.
Most of the day was very entertaining.

The correct verb forms to use in these sentences are as follows:

1. "Behind the stage is a large area for instruments."
Explanation: The subject "area" is singular, so the verb "is" should be used instead of "are".

2. "Few know the results yet."
Explanation: "Few" is a determiner that refers to a small number of people, and it is used with a plural verb. Therefore, "know" should be used instead of "knows".

3. "All of the listeners wait anxiously."
Explanation: "All of the listeners" is a plural subject, so the verb "wait" should be used instead of "waits".

4. "Most of the day was very entertaining."
Explanation: "Most of the day" refers to a singular period of time, so the verb "was" should be used instead of "were".