Things were very expensive those days.You------- a very good

2 选B certainSure与certain是近义词,均作“一定的,确信的”等解。两者用法相似,多数情况下可换用,但有时不能换用。 在“It is…that结构中只能用certain,不能用sure。例如： It is certain that he will come。 毫无疑问他会来It was certain that our football team would win the game。 我们的足球队无疑会赢得比赛如是否定句,用whether,不同that。例如： It is not certain whether he will come。 他来不来还不一定。题目疑问句,同理 教授确定还会再来中国吗?1 选C can/could + have + 过去分词表示对过去某种情况怀疑或者不确定can和could一般用于否定句和疑问句,could语气较弱例句He can't have finished the work so soon他不可能这么快完成工作I didn't see her at the meeting this morning；she can't/couldn't have spoken at the meeting今天早上我没看到她出席会议,她不可能在会上发过言。题目 那些日子物价很高,你只花10块钱是不可能吃到什么好东西的