社会生活的信息化和经济的全球化，使英语的重要性日益突出。精品小编准备了高考英语易错语法知识点，希望你喜欢。

一、定语从句

引导定语从句的关系代词有that, which, who (宾格whom，所有格whose)和关系副词 where when why 等，关系代词或关系副词在定语从句中充当一个成分，关系代词that，which,who,whom等在从句中分别作主语或宾语，whose在从句中作定语，而关系副词when,where,why等在从句中作状语。

如：①I will never forget the days when/in which we worked together.

②I will never forget the days which/that we spent together.

解析：在句①中，表示时间的名词the days在从句中充当的是状语，所以用关系副词when来代指，引导定语从句修饰先行词the days;而在句②中，表示时间的名词the days在从句中充当的是动词spent的宾语，所以用关系代词that或which来代指。

同样，表示地点或原因的名词如果在从句中作状语，则用关系副词where 或why来代指;如果在从句中作动词的宾语，则用which或that来代替。

如：①This is the factory where/in which I worked.(作状语)

②This is the factory that/which I visited years ago.(作宾语)

注：当先行词为time,reason, place时，引导词可以省略。如：

①  This was the first (when/what) I had serious trouble with my boss.

②  That is the reason (why) I did it.

③  This is the place (where) we met yesterday.

另外，定语从句中谓语动词的数应与先行词的数相一致。如：

①  Mr. Jackson is the only foreigner that is present at the party.0

②  He is one of the students who were praised by the teacher.

解析：在句①中，先行词foreigner被only修饰，强调只有一个，所以从句中谓语动词用单数形式，而在句②中，who引导的定语从句修饰先行词the students，为复数，所以从句谓语动词应为复数。

感悟：学生之所以在这一点上经常出错，主要是对定语从句的理解不够深刻，分辨不出主句和从句，对句子成分的把握也不到位，搞不清关系代词或关系副词在从句中充当何种句子成分。所以要做好这一类题，要首先弄清关系代词和关系副词的用法，而且应善于分辨和分析句子结构及其相应成分，这样才能对症下药，快速准确地找到瓿之所在。

二 名词性从句中的易错点

(一)  that引导的定语从句与同位语从句

定语从句与前面的的名词是修饰与被修饰的关系，“……的名词”，而同位语从句是用来说明前面名词的内容。与that从句同位的名词必须是一些表示事实或概念的抽象名词，如fact,news,belief,truth,reply等。That在定语从句中必须作成分，可用which或who/whom代替，而that在同位语从句中不充当任何句子成分，只起连接作用。如：

①Along with the letter was his promise that he would visit me this coming Christmas. ②Do you still remember the chicken farm that we visited three months ago.

解析：在句①中，that引导同位语从句解释说明promise的内容，that不充当任何句子成分，只起连接作用，而在句②中，that在其引导的定语从句中作动词visited的宾语，对先行词the chicken farm起修饰作用。

感悟：学生之所以在这一点上容易出错，主要还是因为对定语从句的理解不够深刻，分辨不出that在从句中是否充当了句子成分，因此，还需在句子分析上下功夫，并且搞清何谓同位语从句。

(二) 名词性从句中，关于it作形式主语和形式宾语的易错点

1.  名词性从句作主语或宾语时，为保持句子平衡，常用it作形式主语或形式宾语。如：

It’s a pity that he don’t come to give a speech.(形式主语)

We think it possible that you can finish the job today.(形式宾语)

2)谓语动词 appreciate, dislike, hate, like, love, make等接由if或when 引导的宾语从句时往往在从句前加上形式宾语it.  例如：I would appreciate it if you could come to my birthday party.

3)动词hare, take, hide, punish, put等,后接由that 引导的病因从句式，往往在从句前加形式宾语it.

例如：① I take it that you will be leaving Shanghai soon.

② we punished it that we had finished the project ahead of time.

4)短语动词answer for, count on depend on, insist on, see to等后接有that引导的宾语从句时，必须冠以形式宾语it.

例如：① I’m counting on it that you will come.

② She’ll see to it that he goes ahead.

注：作形式主语和形式宾语时只能用it.

三、代词it、one、that的用法与区别.

One泛指，指代前面提到的那类人或物，用于指代可数

名词，相当于a+名词单数，其复数形式ones前一般要有定语，否则就要用some.

That(those复数)即可指代不可数名词，表特指，相当于the+名词，后面经常与介词修饰语连用。

It指代上文出现的名词，表示同类同物，另外还可表示时间、距离、天气、还可指代人称代词，表示性别身份不明，可作形式主语，形式宾语，引导强调句式以及一些固定搭配，如：get it, catch it, make it.

例如：① I have lost my watch. I think I must buy one.我丢了只表，我想我必须再买一只。(代指上文指到的同类事物，但不指同一个)

② Where is my pen? Have you seen it? 我的钢笔不知弄到哪去了，你见了吗?(代指上文提到的同一事物)

③ The land of China is larger than that of America.

④ Tome has a red pen and a blue one (或two blue ones)

⑤ He has no child, and he wants to  adopt one (或 some)

四、虚拟语气

I 虚拟语气在if 引导的条件句中的易错点。

① if my lawyer had been here last Saturday, he would have prevented me from going.

② if you had studied hard at school, you would be a college student now.