1 . The flu is believed _________ (cause) by viruses. (所给词的适当形式填空)

2 . 做作业时我想一个人待着。否则, 我就不能集中精力做我正在做的事情。
I’d like to be ______   ______ when doing homework. Otherwise, I couldn’t ______   ______ what I’m doing.

3 . __________ ________ _________ (被劝服）into buying more clothes than necessary is so difficult for women while they’re shopping. （根据汉语提示完成句子）

4 . Don't bother me again! I'd like _______ _______ ________ _________.
别再打搅我了! 我想一个人呆一会。