I know the girl for ----(who) you are waiting

1.whom 定语从句.
可变为：I know the girl who/whom you are waiting for.
因为引导词在从句中作宾语,所以who/whom都可.
但在你的这道题中,把for调到前面了,介词后面必须跟宾格,所以用whom.
2.sleeping.
pretend是一个很重要的词.
pretend to do sth.假装去做某事
pretend doing sth.假装正在做某事
pretend have done sth.假装做过了某事
具体用哪一个根据句意而定.