介词宾语

1. I wonder who/whom they are speaking to.

2. The expressions they use might depend on whom they are speaking to or how well they know each other.

第一句who/whom都对吧；

第二句，我感觉，这个whom是做介词to的宾语，to提前的话，只能是whom, 即： To whom arethey speaking？但目前to没提前，那样whom有没受介词on的影响？可以换成who吗？

谢谢！

句二的depend on是短语动词，在口语中接从句时，on常被省略。比如：

It depends whether you want to do it or not.

句二的depend 接从句和句一的wander接从句一样，所以用who或whom都可以。