5. Look! The cat ______ (sleep) on the sofa.

Explanation:

The word 'Look!' is an exclamation that draws attention to something happening right now. This requires the present continuous tense.

Solution:

The present continuous tense is formed with the auxiliary verb 'to be' and the present participle of the main verb.

1. Subject: The cat (third person singular)
2. Auxiliary verb: is
3. Main verb: sleep + -ing = sleeping

Answer: is sleeping