At first, the speaker was referring to the problem of pollution inthe country, but halfway in her speech, she suddenly（）to another subject.

Your advice would be（）valuable to him, who is at presen...

单项选择题Your advice would be（）valuable to him, who is at present at his wits' end.

She cut her hair short and tried to（）herself as a man.A...

单项选择题She cut her hair short and tried to（）herself as a man.

He has never done this type of work before; I am not su...

单项选择题He has never done this type of work before; I am not sure how he will fit（）with it.