3)that，which，whom在定语从句中作宾语可以省略。如：?

This is the book (which)you were looking for yesterday. 这就是你昨天找的那本书。?

I don’t like the novel (that)you are reading.我不喜欢你看的这本小说。?

4)定语从句中关系代词作主语时，从句的人称、数与先行词一致。如：?

Those who are in their forties are required to have a physical examination this afternoon.?

请那些年龄在四十几岁的人于今天下午去进行体检。?

(先行词those是复数，关系代词who也就看作是复数，所以从句的谓语动词就用了复数形式are了)?

This is the magazine which was sent to me by post.这是通过邮局寄给我的杂志。?

(先行词the magazine是单数，关系代词which也就看作是单数，所以从句的谓语动词就用了单数形式was sent)?

5)定语从句的时态不要求与主句时态一致。如：?

The story which I read last night is very interesting.?

我昨天晚上看的那则故事非常有趣。

3.关系副词的用法?

1)when 指时间，在从句中作时间状语，它的先行词通常有time，day，morning，night，week，year 等。如：?

I still remember the time when I first became a college student.?

我仍然记得我成为大学生的那个时刻。?

Do you know the date when Lincoln was born? 你知道林肯出生的日期吗??

注：when时常可以省略，特别是在某些句型和某些时间状语中。如：?

Each time he came，he did his best to help us.每次他来，都尽他所能帮我们。?

2)where指地点，在从句中作地点状语。它的先行词通常有place，spot，street，house，room，city，town，country等。如：?

This is the hotel where they are staying.这是他们住的旅馆。?

I forget the house where the Smiths lived.我不记得史密斯先生住过的房子了。?

注：where有时也可以省略。如：?

This is the place (where)we met yesterday. 这是我们昨天见面的地方。?

3)why指原因或理由，它的先行词只有reason。如：?

That is the reason why he is leaving so soon.那就是他为什么要离开的原因。?

注：why时常也可以省略。如：?

That is the real reason he did it.那就是他做此事的真正原因。

4.使用关系副词应注意下列几点：?

1)这三个关系副词在意义上都相当于一定的介词+which结构：?

when = on (in，at，during...)+which;?

where = in (at，on...)+which;?

why = for which.如：?

I was in Beijing on the day when (=on which)he arrived.?

他到的时候，当时我正在北京。?

The office where (=in which)he works is on the third floor.?

他工作的办公室在?三楼。??

This is the chief reason why (=for which)we did it.这是我们做这件事的主要原因。?

2)当先行词是表时间的time，day等和表地点的place，house等时，一定要注意分析从句的结构，如果缺少主语或宾语时，关系词应该用which或that,缺少时间状语或地点状语时，才能用when或where，试比较：?

I’ll never forget the day when my hometown was liberated.?

我将永远不会忘记我的家乡被解放的那一天。?

I’ll never forget the days which/that we spent together last summer.?

我将永远不会忘记去年夏天我们共同度过的那段时光。?

3)when和where既可以引导限制性定语从句，也可以引导非限制性定语从句。而why 只能引导限制性定语从句。??