1) The phone is ringing, _______________(但是没人接听。她一定不在家).
2) I can’t find my sunglasses. _______________(我可能昨天落在咖啡店里了).
3) You screamed in your sleep last night. _______________(你一定梦见什么可怕的东西了).
4) It’s a pity. _______________(你本应该邀请她来参加你的毕业典礼的).
5) _______________(其实我没必要穿上我最好的套装去参加那次聚会的); most of the guests were wearing jeans and sweaters.
解析：
1) but there is no answer. She can’t be at home
(考点：情态动词可以表示可能性，can’t 表示“一定不”)
2) I may have left them in the coffee shop yesterday
(考点：“情态动词can/could + 完成式”用于表示对过去发生的动作的主观判断)
3) You must have dreamed of something terrible
4) You should have invited her to your graduation ceremony
“情态动词should/ought to + have done” 用于评论过去应该做而实际并未做的动作5) I needn’t have put on my best suit to go to the party
“情态动词needn’t + have + done”表示对过去发生的动作进行评论，“无须发生”，“不必做”
