（1） 在限定性定语从句中指代物时，which 和that 一般可通用。
The new house that/which I has just bought is about six miles away.
They planted some trees that /which did n't need much water.
(2) 限定性定语从句中只用that 而不用which 的情况。
A）先行词有形容词最高级修饰时
This is the best way that has been used against pollution.
Polly is the most direct young woman that I have ever come across .
B) 先行词有序数词修饰时
This is the third time that they have met.
The very first time that Lester saw the film, he made up his mind to become a doctor.
C)主句已有疑问词who 或which 时
Which of the car s that are in front of the hotel belongs to you?
Who is the man that is sitting by the lake ?
D) 先行词既有人又有物时
He talked about the schools and teachers that he had visited.
The bike and his rider that had run over an old man were taken to the police station.
E) 先行词为all, much, few, little, something, everything, anything, nothing, none 等不定代词时
It's easy to do the repair. All that you need is a hammer and some nails.
I'd like to tell you something that will make you surprised.
F) 先行词前面有the very, the only, the same, any, few, little, no, all, one of 等词修饰时
This is the very room that I slept in that evening.
The only thing that we can do is to give you some money.
Li Ming is the only one that wants to be a teacher.
G) 有两个定语从句，其中一个关系代词宜用which,另一个宜用that。
Edison built up a factory which produced things that had never been seen before.
(3) 只用which 而不用that 的情况
A) 引导非限定定语从句时
The fish, which I bought this morning, is very fresh.
My house, which I bought two years ago, has got a lovely garden.
Jim passed the driving test, which surprised everybody in the office.
Helen was much kinder to her youngest son than to others, which , of course, made the others envy him.
The factory produces half a million pairs of shoes every year, most of which are sold abroad.
(which 前常用none/neither/most/both/each/all/a little of等词修饰)
B）在限定性定语从句中，关系带词前有介词时
I was put in a position in which I had to accept I was less important.
This is the hotel in which you will stay.= That's the hotel (which/that) you will stay in.
(此句中，如果介词in 放在句子的后面，那么关系代词既可用which,也可用that,还可省略。）
C）在限定性定语从句中，如果有两个定语从句时，其中一句的关系代词that 时， 另一个用which.
Let me show you the novel that I borrowed from the library which was newly open to us.
