My father and his teacher talked of things and persons (that)

they remembered in the school.

C.用which不用that：指物，在介词后或引导非限制性定语从句：

I'll never forget the day on which I joined the army.

That was the way (in which) she looked after us.

Football, which is a very interesting game, is played all over the

world.

2.非限制性定语从句

限制性定语从句是先行词不可缺少的定语，而非限制性定语从句

只是附加说明，如果去掉，主句意思仍然清楚。非限制性定语从

句用逗号与主句隔开，由which, who, whom, whose, where, when、

等引导：

His brother, who is a PLA man, wrote to him.(只有一个哥哥)

His brother who is a PLA man wrote to him.(不只一个哥哥)

Football, which is a very interesting game, is played all over the

world.

We'll put off the outing until next week, when we won't be so

busy.

He took out a piece of paper, on which were written some words.

They arrived at a farmhouse, in front of which sat a small boy.

比较："他有两个女儿,其中一个是护士。"

He has two daughters, one of whom works as a nurse.

(非限制性定语从句)

He has two daughters, and one of them works as a nurse.(并列句)

另外，as和which引导非限制性定语从句，可代替整个句子，as指熟知的内容，引导的句子可在句首、句中和句尾；而which指没想到的事情或客观事实，且只能在句尾。比较：

As is known to all, Taiwan belongs to China.

The earth, as we know, goes around the sun.

He is against the idea, as can be expected.

He has to work on Sundays, which he doesn't like.

She remarried, as we had expected.

3.介词+关系代词引导的定语从句

(1)介词+关系代词引导的定语从句，修饰物时用which不用that,

修饰人时用whom不用who。例如：

This is the room in which we lived last year.

Who's the comrade with whom you just shook hands?

(2)注意:固定搭配,介词不能提前。例如：

Is this the book which she was looking for?