例如:This is the house甲I was barn and brought up in the house.在这两个句子中，in the house是句子里的地点状语，定语从句修饰的就是the house。把后面这一句变成定语从句。在将要被变成定语从句的句子中，in the house是地点状语，所以用where来代替它。然后再把where放到本句的最前面，其它的词和语序来代替它。然后再把where放到本句的最前面，其它的词和语序一律不变。这时，就成了"where}was barn and brought up"。再把这个定语从句整个放在被修饰的词后面，就成了"This is the house where I was barn and brought up.”，
　　定语从句就完成了，主句是陈述句，所以句末用句号。Where代替的是原句中的状语，原句变成了从句，它就作从句的状语。
　　(4) The hotel is an artistic building. We' 11 stay in it.
　　……The hotel where we' 11 stay is an artistic building.
　　……The hotel (which/that) we' 11 stay in is an artistic building.
　　……The hotel in which we' 11 stay is an artistic building.
　　(5) Perhaps they' ve heard of the place. We went there for our holidays last time.
　　……Perhaps they' re heard of the place where we went for our holidays last time.
　　定语从句
　　请读者照上面的例子，把下面变定语从句的步骤说出来(括号里的可以省略)：
　　(6)They’re redecorating the room. A conference will be held in the room.
　　→They’re redecorating the room where a conference will be held.
　　→They’re redecorating the room (which /that) a conference will be held in.
　　→They’re redecorating the room in which a conference will be held.
　　那么，“介词+关系代词”是怎么回事呢?原来上面这个例句，还有一种做法：This is the house. I was born and brought up in the house.在这两个句子中，the house是相同的，定语从句修饰的就是the house 。把后面这一句变成定语从句。在将要被变成定语从句的句子中，the house表示物而且是介词in的宾语，所以用关系代词which或that来代替。然后把which或that放到本句的最前面，其它的词和语序一律不变。这时，后面这一句就成了 “which/that I was born and brought up in”。再把这个定语从句整个放在被修饰的词后面，就成了“This is the house which/that I was born and brought up in”。定语从句就完成了，主句是陈述句，所以句末用句号。
　　which/that代替的是原句中的宾语，原句变成了从句，它们就作从句的宾语。关系代词在从句中作宾语时可以省略，因此上句又可变成“This is the house I was born and brought up in.”
　　但是，in可以提到关系代词的前面，不过这时不能用that，而且不能省略。所以上句又可变为“This is the house in which I was born and brought up.”这就是“介词+关系代词”的来历。
　　定语从句又分为限定性定语从句和非限定性定语从句。限定性定语从句把它的先行词限定在特定的意义之内，对先行词起限定的作用、是先行词必不可少的修饰语，没有它，整个句子的意思就会受到影响、就不完整。非限定性定语从句不对先行词起限定的作用，不是先行词必不可少的修饰语，只对先行词起补充说明的作用，没有它，整个句子的意思不会受到影响、仍然完整。非限定性定语从句相当于一个分句，翻译时也是把它当作分句处理的。非限定性定语从句和它的先行词之间要用逗号隔开;而限定性定语从句和它的先行词之间不能用逗号隔开。非限定性定语从句中除了不用that以外，其它关系词都可使用，使用方法与限定性定语从句一样。
　　例如：The supermarket which was opened two months ago is now closed down.
　　两个月前开的那家超市现在已经倒闭了。(限定)
　　The supermarket, which was opened two months ago, is now closed down.
　　那家超市现在已经倒闭了，那家超市两个月前开的。(非限定)
　　The book(which) you’re reading is mine .
　　你正在读的那本书是我的。(限定)
　　The book, which you’re reading, is mine.
　　那本书是我的，你正在读那本书。(非限定)
　　如果以上例子的差别不十分明显，再看下面的例句：
　　I’ve been to London , which is a beautiful city。