that what which怎么辨别?

that
adj.
那,那个
At that time he was very busy.
那段时间他很忙.
pron.
那,那个
What was that which he gave you?
他给你的是什么?
conj.
(用于引出各种从句)
It's the best that you should work hard.
你最好还是努力工作.
what
pron.
(用以询问某人或某事物的词) 什么,多少
What is the price?
价钱多少?
…的事物
This dictionary is just what I want for my study.
这部词典正是我学习要用的工具.
adj.
…的(事物或人)
What colour is it?
它是什么颜色的?
adv.
(用于感叹句中)
What genius he has!
他真有才华!
int.
(用以表示不相信或惊奇)
What,do you really mean it?
什么,你真是这个意思?
(用以表示未听清楚对方说的话)
What?Can you say that again?
什么?你能再说一遍吗?
which
pron.
哪一个,哪一些
That is the house which I built.
那是我建的房子.
adj.
哪一
Let me know which train you'll be arriving on.
告诉我你要坐哪一趟车来.