回答In three weeks 表示在三周内,所以问句应该是问什么时候会回来
那么how often是频率,回答不用in
how long是多久 后面回答需要用for
how soon soon 有多久的意思
所以这里要选CI didn't buy the English-chinese book( )my mother had bought one for me.B.when C.while()good time they are having now!( )great fun it is!A.What;What a B.What a;What C.How;What D.How a;What a我喜欢在外面翻译为I( )( )outside快点啊。。我没分了！whilewhat a; whatI like go