词汇和语法是考研英语的基础，有了它们英语学习才能够融会贯通，不断深入。著名语言学家乔姆斯基说过，语法是内生的、也就是随着语言的诞生而诞生的。因此，学习语法和学习语言是相辅相成的。可是很多同学往往都注重对词汇的积累，忽略了对语法的把握。下面比网校在线小编分享2015年考研英语：十二大基础语法详解，希望通过学习，考生能够熟练掌握语法知识，提高做题效率。
下面请看2015年考研英语：十二大基础语法详解（28）
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肯定句 |
否定句 |
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We/'ve had some money. |
We haven/'t had any money. |
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I was talking to someone |
I wasn/'t talking to anyone. |
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They sometimes visit us. |
They rarely (never, seldom) visit us. |
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He has arrived already. |
He hasn/'t arrived yet. |
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Li is coming too. |
Li isn/'t coming either. |
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Both of us are going. |
Neither of us are going. |
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He likes both of them. |
He doesn/'t like either of them. |
注意：“so/neither+助动词/情态动词+名词/代词”结构中须用倒装语序，
如：My wife likes classical music very much and so do.
She doesn/' t like jazz and neither do.
七、定语从句
所谓从句，就是一个主谓结构相当于整个句子(这样的句子叫复合句)的一个成分，因此，从句不能单独使用。在复合句中修饰名词或代词、作定语的句子叫定语从句。定语从句是中国人学英语最重要的难点之一。
其实定语从句很有规律，总结如下:在关系代词中that既可指人又可指物、既可作主语又可作宾语，因此，除了在非限定性定语从句中，用that一般不会出问题。
关系副词的用法比较单一，它们从句中只起状语的作用，表示时间的就用who门，表示地点的就用where，而why只修饰一个词，即reason。
定语从句所修饰的词叫“先行词”，因为它总是处在定语从句的前头，比定语从句先行一步。
引导定语从句的词叫关系词，包括关系代词和关系副词。
关系代词：
who，which，that作从句的主语
whom，which，that作从句的宾语(可省略)
whose从句中作定语
以下情况只能用that，不能用which:
i. 先行词为不定代词all, little, none，any，every，no，much, anything, nothing
ii. 先行词有最高级和序数词修饰时(包括: the only, the very, the same, the last, the next等)
iii. 先行词既有人又有物的时候
以下情况只能用which，不能用that;
① 引导非限制性定语从句(包括代表整个主句的意思时)
② 介词+关系代词的结构中
关系副词：
when指时间，在定语从句中作时间状语
where指地点，在定语从句中作地点状语
why指原因，在定语从句中作原因状语，只修饰reason。
如果用定语从句把两个句子合二为一:首先找出两个句子当中相同的部分，定语从句修饰的就是这一部分。要把其中一个句子变成定语从句，就要把这句中相同的那个部分用一个关系词来代替;代替时，先看被代替的部分是指人还是指物、再看它作什么句成分。指人并作主语的，就用who。或that;指人并作宾语的，就用whom或that;指人并作定语的，就用whose。指物并作主语的，就用which或that认指物并作宾语的，还是用which或that认是物并作定语的，就用whose或of which。这样找好并替换以后，再把这个关系代词放到要变成定语从句的那个句子的最前面(被代替的部分不能再保留，其它的词语一律不变)，这个句子就变成了定语从句。然后，再把这个定语从句整个放在被修饰的词后面，最后，如果还有其它句子成分，就把它们放到定语从句的后面，就行了。
例如：
Have you found the book? You were looking for the book yesterday.
在这两个句子中，the book是相同的，定语从句修饰的就是the book。把后面这一句变成定语从句，找个关系词来代替the book;在将要被变成定语从句的名子中，the book是物并作宾语，所以用which或that代替它。
然后把which或that放到本句的最前面，其它的词和语序一律不变。这时，就成了"that/which you were looking for yesterday?”，再把这个定语从句整个放在被修饰的词后面，就成了“have you found the book that/which you were looking for yesterday?”定语从句就完成了，主句是问句，所以句末用问号。that/which代替的是原句中的宾语，原句变成了从句，它们仍然作从句的宾语。关系代词在从句中作宾语时可以省略，因此上句又可变成“have you found the book you were looking for yesterday?”.
关系副词与此同理。只是关系副词代替的是原句中的状语。在被代替
之前，这个状语中一定要含有一个与另一句相同的成分。
例如:This is the house甲I was barn and brought up in the house.在这两个句子中，in the house是句子里的地点状语，定语从句修饰的就是the house。把后面这一句变成定语从句。在将要被变成定语从句的句子中，in the house是地点状语，所以用where来代替它。然后再把where放到本句的最前面，其它的词和语序来代替它。然后再把where放到本句的最前面，其它的词和语序一律不变。这时，就成了"where}was barn and brought up"。再把这个定语从句整个放在被修饰的词后面，就成了"This is the house where I was barn and brought up.”，
定语从句就完成了，主句是陈述句，所以句末用句号。Where代替的是原句中的状语，原句变成了从句，它就作从句的状语。
(4) The hotel is an artistic building. We' ll stay in it.
……The hotel where we' 11 stay is an artistic building.
……The hotel (which/that) we' 11 stay in is an artistic building.
……The hotel in which we' 11 stay is an artistic building.
(5) Perhaps they' ve heard of the place. We went there for our holidays last time.
……Perhaps they' re heard of the place where we went for our holidays last time.
定语从句
请大家照上面的例子，把下面变定语从句的步骤说出来(括号里的可以省略)：
(6)They’re redecorating the room. A conference will be held in the room.
→They’re redecorating the room where a conference will be held.
→They’re redecorating the room (which /that) a conference will be held in.
→They’re redecorating the room in which a conference will be held.
那么，“介词+关系代词”是怎么回事呢?原来上面这个例句，还有一种做法：This is the house. I was born and brought up in the house.在这两个句子中，the house是相同的，定语从句修饰的就是the house 。把后面这一句变成定语从句。在将要被变成定语从句的句子中，the house表示物而且是介词in的宾语，所以用关系代词which或that来代替。然后把which或that放到本句的最前面，其它的词和语序一律不变。这时，后面这一句就成了 “which/that I was born and brought up in”。再把这个定语从句整个放在被修饰的词后面，就成了“This is the house which/that I was born and brought up in”。定语从句就完成了，主句是陈述句，所以句末用句号。
which/that代替的是原句中的宾语，原句变成了从句，它们就作从句的宾语。关系代词在从句中作宾语时可以省略，因此上句又可变成“This is the house I was born and brought up in.”
但是，in可以提到关系代词的前面，不过这时不能用that，而且不能省略。所以上句又可变为“This is the house in which I was born and brought up.”这就是“介词+关系代词”的来历。
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