O-Level语法：定语从句的注意事项

　　在O-Level英语备考中，很多小伙伴除了词汇不过关，其次就是语法了，今天课窝考试网继续分享关于定语从句的语法盲区分析，希望大家能都认真的对待这部分的内容，因为这一定会在考试中对你有所帮助。

　　(一) 关系代词和关系副词的省略

　　1. 关系代词的省略

　　1) 关系代词在从句中作宾语时可以省略

　　I have been to the city twice (that/which)you just visited.

　　2) 关系代词在从句中作表语时可以省略

　　The village is not the one (that)it was years ago.

　　3) 关系代词在从句中作介词的宾语,而介词在从句句尾时可以省略.

　　Generation gap is a problem(which/that) people are interested in.

　　2. 关系副词的省略

　　1）先行词the place后的关系副词可省略。

　　That’s the place (where) he lived when he was in Paris.

　　2) 先行词the reason后面的关系副词或省略。

　　That’s the reason (why) I asked you to come.

　　3) 当先行词是way时，关系副词常常可以省略。

　　I don’t like the way (that) you speak to me.

　　(二) 先行词有下列情况或附有下列修饰语时, 通常关系代词用that

　　1)先行词是all， no， none， everyone， something， much， little等。

　　2)先行词前有序数词,形容词最高级，the last， the same， the only等。

　　3)如果先行词中既含有表示人的名词又有表示物的名词时。

　　4)若主句中有疑问代词who，which 为了避免重复, 关系代词不要再用who， which

　　（三）下列情况中通常不用that

　　1) 关系代词前有介词时

　　2）在非限制性定语从句中

　　3）先行词本身就是that时，

　　What is that which flashed in the sky just now?

　　4) 先行词是指人的不定代词时

　　One who has nothing to fear dares to tell the truth.

　　5) 当先行词指人并含有较长的后置定语或在被分割的定语从句中时

　　The boy was crying hard who lost his way.

　　（四）as, which引导的非限定性定语从句

　　由as, which 引导的非限定性定语从句，as和which可代整个主句，相当于and this或and that。As一般放在句首，which在句中。

　　As we know, smoking is harmful to one's health.

　　The sun heats the earth, which is very important to us.

　　as 和which在引导非限制性定语从句时，这两个关系代词都指主句所表达的整个意思，且在定语从句中都可以作主语和宾语。但不同之处主要有两点：

　　(1） as 引导的定语从句可置于句首，而which不可。

　　(2） as 代表前面的整个主句并在从句中作主语时，从句中的谓语必须是系动词；若为行为动词，则从句中的关系代词只能用which.在本题中，prevent由于是行为动词，所以正确选项应为B。

　　As we know, smoking is harmful to one's health.

　　As is known, smoking is harmful to one's health.

　　As是关系代词。例1中的as作know的宾语；例2中，它充当从句的主语，谓语动词know要用被动式。

　　注意：“as/which”特殊定语从句的语义功能

　　关系代词as和which引导的定语从句as和which引导非限制性定语从句，有相同之处也有不同之处。具体情况是：

　　1. As和which都可以在定语从句中做主语或者宾语，代表前面整个句子。

　　(1) He married her, as/which was natural.

　　2. as 引导非限制性定语从句, 可放在主句之前, 或者主句之后, 甚至可以切割一个主句; which引导的非限制性定语从句只能放在主句之后. 另外，as有“正如……, 正像……”的意思

　　(1) As is known to all, China is a developing country.

　　(2) He is from the south, as we can see from his accent.

　　(3) John, as you know, is a famous writer.

　　注意：当主句和从句存在逻辑上的因果关系时，常用which

　　(4) Tom was always late for school, which made his teacher angry.

　　3. 当先行词受such, the same修饰时，常用as

　　(1) I have never heard such a story as he tells.

　　(2) He is not such a fool as he looks.

　　(3) This is the same book as I lost last week.

　　注意：当先行词由the same修饰时，偶尔也用that引导定语从句，但是和由as所引导的定语从句意思不同

　　(4) She wore the same dress that she wore at Mary’s wedding.

　　(5) She wore the same dress as her young sister wore.

　　注意：定语从句such…as …与结果状语从句such… that…的区别：as在所引导的定语从句中作主语，宾语；that在结果状语从句中不做成分

　　(6)He has such a good laptop as I want to buy.

　　(7)He has such a good laptop that I want to buy one.

　　以上就是小编为大家整理的关于O-Level英语语法中定语从句注意事项汇总，希望对大家有所帮助。更多o-level可以申请大学吗、新加坡o水准成绩查询等问题可以咨询我们。