as is mentioned above(正如上面所提到的)等。而which 常被译为"这一点，那"，并且主句和从句常存在逻辑上的因果关系。

　　A five­year­old boy can speak two foreign languages, which/as surprises all the people present.

　　一个五岁男孩会讲两门外语，这令在场的所有人感到惊讶。

　　Tom was always late for school, which made his teacher very angry.

　　汤姆上学总是迟到，这让他的老师很生气。

　　As can be seen from his face, he is quite pleased.

　　从他的表情可以看出来，他非常高兴。

　　2．关系副词引导的非限制性定语从句

　　当先行词指时间或地点时，用when, where引导非限制性定语从句，在定语从句中作状语。why不引导非限制性定语从句，但可用for which代替。

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

　　我们将把郊游推迟到下个星期，那时我们就不会那么忙了。

　　Many children go to a day care centre, where they can learn games.

　　很多孩子上日间托儿所，在那儿他们可以学习游戏。

　　3．"名词/代词＋介词＋关系代词"结构

　　此类结构常见的有some/several/a few/a little/many/more/most/the largest ...of which/whom等形式。

　　Here are the questions, some of which I thought are difficult for you.

　　问题都在这儿，其中一些我认为对你来说太难。

　　He has many friends, three of whom are from foreign countries.

　　他有很多朋友，其中三个来自外国。

　　定语从句的省略

　　1．省略作宾语、表语的关系代词

　　在限制性定语从句中，当关系代词在从句中作宾语或表语时，关系代词可以省略。

　　The boy (that/who/whom) we saw last night was Li Ming.

　　我们昨晚见到的那个男孩是李明。

　　Who is the man(that/who/whom) you were talking to?

刚才和你讲话的人是谁？