5 He has to finish his homework today. He ———— his homework last night.

• The first sentence uses 'has to finish' indicating a present obligation.
• The second sentence refers to 'last night', indicating a past event. Therefore, the auxiliary verb for the past tense negative is needed.
• The phrase 'have to finish' is not suitable for the past tense negative. The correct form is 'didn't have to finish' or 'couldn't finish' if the intention was inability. However, given the context and the usual structure of such exercises, 'didn't' is the most probable answer to form a negative past statement.

Answer: He didn't finish his homework last night.