Write two sentences for each situation. Use needn't have in the first sentence and could have in the second (as in the example). For could have, see Unit 27.
2 Why did you walk home? Why didn't you take a taxi?
3 Why did you stay at a hotel? Why didn't you stay with us?
4 Why did she phone me in the middle of the night? Why didn't she wait until the morning?
5 Why did you shout at me? Why weren't you more patient?
6 Why did you leave without saying anything? Why didn't you say goodbye to me?