尽量不要查字典!
1)The book ______ is now out of stock
A. which he bought it last week
B. which he bought last week
C. which he had bought last week
D. which it was bought last week
解题思路：如果你选择了A或D，说明你对"句子成分"的概念，或对关系代词在句子中可以做什么成分还不清楚，应该好好复习"什么叫定语从句?"一节;如果选C，说明你对时态概念仍不清楚，再复习"过去完成时"一节;正确答案为B，"which"在从句中做动词bought的宾语。这里能不能将"which"改成"that"呢?当然可以，而且现在更多的是用"that".实际使用中，该句子中的"which"或"that"可以省掉，即：The book he bought last week is now out of stock. (他上周买的那本书现在脱销。) ,即：当关系代词在从句中当宾语时，可以省掉。
2) He is the man ______ is capable of finishing this task.
A. he
B. whom
C. who
D. which
解题思路：正确答案为C，关系代词在从句中当主语，故选择主格who而不是whom;任何A、D选择说明学生缺乏最基本的语法概念，应补最基础的语法课。
3)The only thing _____ can be done is to stop them from going there.
A. which
B. that
C. what
D. who
解题思路：记住：定语从句中永远不可能出现what做连接词, 记住这句话对理解"名词性从句"会大有帮助; 既然先行词为thing(事情), 就不能用who连接;同时出现"which"和"that"，又没有"，"号，当然选B(the only thing只能用 that连接，不能用 which连接)。下面一题的思路是一样的：
4)All ______ is a continuous supply of the basic necessities of life.
A. which is needed
B. that is needed
C. what is needed
D. is needed
正确答案是：B 注意：all that = what, 不可能出现all what
5) Some of the roads have been flooded(淹没), ______ our journey more difficult.
A. it makes
B. they make
C. which makes
D. which make
解题思路：四个答题中有两个区分点：第一个区分点是：C、D都用了连接词"which"，而A、B没有用，根据"逗号不能连接两个句子"的原则，A、B肯定不对;第二个区分点是：C、D中，动词一个用单数形式makes，一个用复数形式，这里应选择C.为什么?非限制性定语从句中，除了说明先行的某个名词外，还可以说明整个句子的内容，此时动词用单数形式。全句意思：有的路已被洪水淹没，这使我们的旅行更加困难。"which"代表"有的路已被洪水淹没"这件事情。
考试时，当出现类似形式的题目而确实又看不懂句子意思时，应倾向于选择which + 单数动词的那个选项。
6)They have made another wonderful discovery, ______ of great importance to science.
A. which I think is
B. I think which is
C. which I think it is
D. I think of which is
解题思路：英语中的连接词一般都是放在从句的最前面，据此，可以排除B、D选项;A、C的区分点是"it", 想一下本节的第一题，就能正确选择答案A了。此类题目中，I think应理解为"插入语"，要熟悉这种形式，
又如：
He is the man ______ I suppose is capable of finishing this task.
该题应填who而不是whom
(在从句中)当状语时：关系副词where及when
where : 当先行名词在从句中当"地点状语"时，用关系副词where连接
例如：
The crime rate rises in cities where the unemployment rate increases. (失业率高的城市犯罪率也高。) 句中的where = in cities, 表示行为发生的地点。
这里的要点是能否区分是用that (which)还是用 where， 即：是做"主语、宾表语"，还是做"地点状语"，例如：
I love the small town that we visited last week.
句中"town"做动词"visited"的宾语，即"参观过的小镇"，故用that连接。
I love the small town where I lived during my childhood.
句中"town" 是动词"lived"的地点，即"童年时住过的小镇"，故用where.
这也是定语从句的一个考点。
when : 当先行名词在从句中当"时间状语"时，用关系副词when连接, 例如：
July is the month when we have a lot of rain. (七月是多雨的月份。)
注意"when"定语从句后推的现象，例如：
I think (that) the day will finally come when air pollution can be put under control. (我认为空气污染得以控制的一天最终会来到。)
