1定语从句中不同的引导词的使用
2定语从句中的省略用法
1) that, which, whom, 若在从句中做宾语时可以被省略
例: Mary likes the book (that/which)her mother bought yesterday.
2) that, which, who 在从句中做主语时，“主+系”经常可以同时省略，即that+be，which+be，who+be 可同时省略，转换成形容词短语结构或者doing,done的非谓语动词结构置于名词后进行修饰
例：
1.Victoria is totally absorbed by the books (that/which were )written by Dickens.
2.I know the girl(who is)standing there.
3.his book describes some artisans (who were) famous in the past.