人物：先行詞既有人又有物時
Students talked about persons and things that they saw in Yanxigonglue.
I can remember persons and things that I saw in the room.
高：先行詞被形容詞最高級修飾時
She is the most beautiful girl that I have ever seen.
This is the most interesting film that I have ever seen.
序：先行詞被序數詞修飾時；
This is the last thing that I want to do.
The first letter that I got from him will be kept.