10. Listen! The birds ______ (sing) in the garden.

Explanation:

The exclamation 'Listen!' draws attention to an action happening right now. Therefore, the present continuous tense is required.

Solution:

The present continuous tense uses the auxiliary verb 'to be' followed by the present participle of the main verb.

1. Subject: The birds (third person plural)
2. Auxiliary verb: are
3. Main verb: sing + -ing = singing

Answer: are singing