Question

20. ―You didn't wait for Mr Smith last night, did you?

―Yes, but we    . He didn't return home at all.

A. don't have to      B.  needn't have

C. don't need to     D. should have

Answer 1

20.   B考査情態(tài)動詞。句意："你們昨晚沒有等史密斯先生，是嗎？""不，我們等了，但實(shí)際上沒有必要，因?yàn)樗�（昨晚）根本就沒回家。"本句中yes表示昨晚，了史密斯先生。但從下文中看出，他根本就！回家。所以可知"本沒有必要等"。need not have done表示的意思是"本不需要做"。本題have 后省略了 waited,其他選項(xiàng)不符合句意。