一.先行词对定语从句中的动词的制约。

1. I , who am you friend, will help you certainly.

学习者受疑问句Who is that man? Who is coming?　等的影响，在定语从句中也用is，忘记了先行词是I，后面的动词应为am。

2. He is one of the teachers who know French in our school.

在定语从句的习惯使用中，one of后面的名词是复数，这个复数名词制约后面的定语从句的谓语动词，因而know不作加s. 而在one of 前面有the或 the only时，后面引导的定语从句中的谓语动词则用单数形式。如：

3. He is the only one of the teachers who knows French in our school.

而在现代英语中我们也可以见到在one of 加名词复数的后面定语从句作单数动词的情况：

4. This is one of those novels which begins with an idea.

然而在测试中我们还是按习惯用复数动词为宜。

二.主句和从句的时态可以不一致

5.Tom, who is my friend , came to see me yesterday.

在定语从句中，据需要可以用一般现在的状态，如who is my friend这个从句中，就要用现在时。初学者往往以为主句用过去时，则从句也用过去时。实际上主句和从句的时态是根据意义需要来决定的而不同。

三.在从句中使用了多余的代词

6、I’ll give you the book which you’ll find it interesting.

定语从句中的it是多余的，因为which 已经代表了the book 在定语从句中做了find 的宾语。不能又it来做它的宾语。

四.漏了关系词

7.I met the man stole my watch.

受汉语影响，学生的练习中经常写出这类句子。英语的一般特点就是如果有从句出现，从句要有引导词引导这从句。只有个别的句子才有省略引导词的，一般是不宜省略引导词的。

五.漏了应带的介词

8.Let’s find a room which we can put our things in.

在先行词需要在定语从句中作介词的宾语时，这个介词是不能漏的，如此句中的in。因此在学习中先要明确先行词在定语从句中是做主语还是做状语。在这句中room在定语从句中是做put in 的宾语的，如果在这句中的room要做定语从句的地点状语，则关系词which改为where也可。

介词是在先行词为time, place, way等等时才有省略。

六.分清介词是属于哪一部分的

9. This is the town that she lived in Germany when she was young.

在she lived in Germany里有介词in,但它不是lived in the town的结构，而是the town in Germany的结构，也就是说in是后面的，那么lived后面就少了一个in. 正确的可以是：

10. This is the town where she lived in Germany when she was young.

11. This is the town which she lived in in Germany when she was young.

七.分不清先行词是在从句中做主语还是做宾语

12. This is the house where they lived last year.

13. This is the house (which/that) they built last year.

在12句中house在定语从句中做地点状语，所以关系词用where; 在13句中house在定语从句中做宾语所以用which/ that 或者省略。

14. This is the time when we left.

15. This is the time that reminded us of the happy life in out school.

在14句中，time在定语从句中做了时间状语，而在15句中，time则做了主语。所以用的引导词不同。

八.分不清定语从句还是其他从句

a. 定语从句还是状语从句

16. Here is such a big stone as no one can move.

17. Here is so big a stone as no one can move.

18. Here is such a big stone that no one can move it

19. Here is so big a stone that no one can move it.

在16，17句中as 都在定语从句中做了move 的宾语，as是引导词，引导定语从句，而在18，19句中，that 上作来引导状语从句的。

20.I’ll go to the place where you stay.

21. I’ll go where you stay.

在句20中where是引导定语从句，而在句21 中where是引导在点状语从句的。

b. 定语从句还是主语从句

22. As is known to all, they are sure to win.

23. It’s known to all that they are sure to win.

在句22中as是关系代词，代表后面的整个句子做主句的主语。在句23中it是代词，代表that引导的句子做主句的主语。

九.看不出插入句部分，以为是定语从句，影晌句中动词的选择

24. I met a man who I thought _____ to help us.

a. would come b. of coming c. to come d. come

许多学生一看though马上就想起think of doing sth而选了c. 然而在这里I thought是一个插入成份，如果将其省掉就容易看出who是后面的主语了。同样who也不会用whom 了。

分辨不出限制性定语从句，非限制性定语从句有一些分别：

25. All the books here, which have beautiful pictures in them, were written by him.

26. All the books here which have beautiful pictures in them were written by him.

句25 一般表示所有的书都是他写的。句26则表示所有有图画的书是他写的。

27. My father, who works in Shanghai, writes to me twice a month.

28. My father who works in Shanghai writes to me twice a month.。

同样27，28一般的情况下是略有不同意义的。想想下句,如无逗号意义怎样。

29。He sent a letter to his wife, who works in the south of China.

十.冠词处理不好

学习者往往以为定语从句是对前面的名词有限定作用，那么则是特指了，先行词如有寇词则一定是the了，其实不然。

30. A sailor is a man that works in a ship。

31. He is the man that helped me yesterday。

要知道，有的定语从句只是对前面的名词作说明或解释。句30的定语从句是对行词作说明，说水手是一种。。。人，那是泛指的，不用the。而句31的定语从句是才特指的。

32 Is this factory_______ you visited last year?

a. the one c. that c. which d. where

33. Is this the factory_______ you visited last year?

a. the one c. that c. who d. where

十一。独立句与定语从句分不清

34. I met twenty students, some of whom are good at maths.

35. I met twenty students. Some of them are good at maths.

36. We reached the mountain, on the of which we saw a beautiful scene

37. We reached the mountain. On the of it (or: On its top ) we saw a beautiful scene

34 和36是主句和定语从句关系，所以我们要用关系代词，而在35，37各两句中，它们是各自的独立句子，所以用代词。当然在36中将on the top of which改为on whose top,则定语从句的关系 更为明显。

十二。分不清同位语还是定语从句

38. We heard the news that pleased everyone.

39. We heard the news that our term had won.

在这里要认清楚定语从句的关系词在从句中起句子成份作用，而同位语的that 不充当句子成份，句38中的that就充当了从句中的主语，在句39中that却不在从句中充当任何成份。再者同位语从句引导词还可以由其他的词来引导。如：

40. I have no idea what he going to do.

41. I have no idea whether he will come.

42. I have no ides where he will go.

十三。关于复合关系代词whoever, whatever等等

43.Whoever get the job will have a lot of work to do.

44. Whoever gets the job, he will have a lot of work to do.

45. Whatever she says goes.

46. Whatever she says, it goes.

在句43中whoever=anyone that 即有定语从句的意味，在句45中whatever=anything that也有定语从句的意味。而在44和46句中的whoever和whatever则是引导状语从句，所以它们后面的句子都有主语。

十四。定语从句与what引导的名词性从句的转换

47. He’s not the man that he was.

48. He’s not what he was.

49. China is no longer the country that it was.

51. China is no longer what it was.

我们常用名词+that改变成what的形式，如47，48句，它们的意义基本上是一样的，只不过用名词+that更为清晰。49，50句也是如此。