定语从句后面的动词怎么是ed形式

定语从句中的动词的时态要根据具体情况选择，不一定都是-ed形式。
如 I like the girl who walks to school everyday.
I like the girl who danced yesterday.
I like the girl who has finished her college study.

定语从句的用法
定语从句由关系代词who、whom、whose、which、what、as和关系副词where、when、why等引导，但须记住：
1.what不能引导定语从句.
2.关系词的分析须考虑它在定语从句中的成分。
一.指人的关系代词有who、whose、whom、that. 试分析：
The old man who/whom /that we visited yesterday is a famous artist.
Miss Wang is taking care of the child whose parents have gone to Beijing .
The man with whom my father shook hands just now is our headmaster. （=The man who/whom that my father shook hands with just now is our headmaster.）注：
A． 指人时有时只用who不宜用that。
1．先行词为one、ones或anyone
（1）The comrade I want to learn from is the one who studies hard and works hard.
（2）Anyone who breaks the law should be punished.
2．先行词为these时
These who are going to Beijing are the best students of our school.
3．在there be 开头的句子中
There is a student who wants to see you.
4．一个句子中带有两个定语从句，其中一个定语从句的关系代词是that，另一个宜用who，以免重复。
The student that won the first prize is the monitor who works hards.
5．在非限制性定语从句中
A。I met a friend of mine in the street, who had just come from Japan.
B．主句以who开头的句子中,只用that,不用who。

that和which引导定语从句的区别
that \which在代物时常常可以通用,但有时只宜于用which ,不用that

(1) 关系代词前有介词时.

This
is the hotel in which you will stay.

(2)
如有两个定语从句,其中一句的关系代词是that,另一句宜于用which.

Let me show you the novel that I
borrowed from the liberary which was newly open (新开放) to us.

注意2that
\which在代物时常常可以通用,但有时只宜于用that ,不用which.

(1) 先行词是形容词最高级或者它的前面有形容词最高级时

This is the best that has been used against air pollution(反对空气污染) in
cities.

English is the most difficult subject that you will learn during
these years.

(2) 先行词是序数词,或它的前面有一个序数词时

He is the last person that
I want to see.

(3) 主句中已有疑问词时

Which is the bike that you lost?

(4) 先行词既有人又有物时

The bike and its rider that had run over (撞倒了)an
old man were taken to the police station.

(5)
先行词是all,much,little,something,everything,anything,nothing,none,the one等代词时

You should hand in all that you have.

We haven’t got much that
we can offer you.

I mean the one that you talked about just now.

(6) 先行词前面有only,any,few,little,no,all,one of,the same,the very等词修饰时

The only thing that we can do is to give you some money.

Li Ming
is the only one that got full marks (满分)in our class.

Li Ming is one of
the students that want to be teachers in our class.

(7)
有两个定语从句,其中一个关系代词已用which,另外一个宜用that

Edison built up a factory(办了一个工厂)
which produced things that had never been seen before.

定语从句的关系副词
Where的用法:若先行词指地点且其在定语从句中充当地点状语.

This is the house+I was born in the
house. (=I was born there)

介词短语 副词

=This is the house where I
was born.这就是我在那儿出生的房子.

先行词 关系副词

in which I was born.

介词+关系代词

which I was born in.

关系代词

这里作介宾的which和that可以省略

定语从句中的动词的时态要根据具体情况选择，不一定都是-ed形式。
如 I like the girl who walks to school everyday.
I like the girl who danced yesterday.
I like the girl who has finished her college study.

你好
定语从句后面的动词形式有很多
比如加ing、ed、不定式
而加了ed来修饰的
一般情况下要么是被动语态
要么是过去式或者现在完成时
比如I saw the boy who helped me yesterday.
这是一个典型的过去式 所以加ed
别的还有很多的时态需要具体分析
满意请采纳