1、选A occasion n. 时机,机会;场合;理由
2、选A 过去式,直接排除B\C\D
3、选C it is impossible for sb. to do sth.
4、选A 此处需加将来完成时
5、选C which(指前面所说过的内容,尤其要发表个人意见时)
例:They ran out of drink. Which actually didn't bother me because I wasn't drinking.
他们没有酒了,这个其实对我倒无所谓,因为我当时没在喝酒。
以上,希望可以帮到你,望采纳。
A A C A C
A A B C A