I hate it when people talk with their mouthe full是2004年哪个省的高考题

你好.在我记忆中好像是福建省的,不过哪个省的高考题不重要.
这是宾语从句.it 是形式宾语,when people talk with their mouthe full是真正宾语.又如,
1 I like it when summer comes（when- --- comes是真宾语,it是形式宾语）
2 We will appreciate it if you can help us（it是形式宾语,if - - us是真正宾语）
注意,这一句是条件状语从句：I don't mind if you can't join us (注意 mind后面没有it)