Fill in the gaps with the correct form of the verbs in brackets. Use the FULL form. A: You look woried. What (happen)? B: I (not/pay) pay the bills last month.

Okay, let's fill in the gaps with the correct verb forms.

A: You look worried. What happened?

Explanation: Here, 'happen' is used in the past simple tense because the question is about something that occurred earlier and made the person worried.

B: I did not pay the bills last month.

Explanation: The sentence indicates an action that didn't occur in the past. Therefore, the past simple negative form of 'pay' is used: 'did not pay'.