英语语法：连词的用法和从属连词
连词：连接单词与单词、词组与词组、句子与句子、从句与主句的词叫连词。
连词也是虚词，不能独立作句子成分。
连词分为并列连词和从属连词两种，并列连词用于连接两个或者两个以上并排列举的单词、词组或者句子，从属连词用于连接从句和主句。
1.连接状语的连词最多
表时间：
before, after, when
as, while, since
till, until, as soon as
And before that? Before that, not even the sun, our good old sun,our good old sun, was there.
那么在那以前呢?在那以前，甚至太阳，我们可爱又古老的太阳也不存在。
Nike didn’twait until dinnertime until they sent out a press release saying they were suspending the relationship.
耐克在晚餐前便发布新闻稿表示将暂停和莎拉波娃的合同。
表条件：
if, if only(只要)
only if(只有),as long as(只要)
on condition that, provided (that)
We might cook this little mouse, if only we had some stuffing!
我们只要有一些填料，就可以煮了这个小老鼠。
You may keep the book a further week provided that no one else requires it.
倘若这本书没有其他人想借的话，你可以续借一个星期。
表让步：
though, although
even if, even though
though the buyer ended up stiffing him for half of that.
但是最后买家只给了一半的钱。
No fans will be permitted into the game even ifthey bought tickets.
即使买了门票，粉丝们也不能进去。
其他：
whether, than, lest(生怕)
unless(除非)，because
as if, as though(好像)
so that, where, wherever
I shall look as if I were suffering. I shall look a little as if I were dying.
我将会像是很痛苦的样子……我有点像要死去似的。
He said it’s as if the crew played a computer game.
他表示这就好像是车载人员在玩一款电脑游戏。
2.连接主语从句、表语从句和宾语从句的连词
纯连词：
that, whether, if(注：if不能用于主语从句)
It is surprised for me that my father has much money.
使我惊讶的是，我爸有许多钱。
连接副词：
when, where, how, why
Work hard when youare at work and have a good rest when you are free.
工作时努力工作，休息时好好休息。
That is why Ican’t catch the train.
那就是我没有赶上这班火车的原因。
连接代词：
what, which, who, whose
What will matter is not what you learned, butwhat you taught.
重要的不是你所学的而是你所授的。
It is superpower-in-waiting whose people vote,whose society is raucous, and whose firms are red-blooded and striding onto the world stage.
印度正在成长为一个超级大国，民众拥有选举权、社会充满活力、商业蓬勃发展大步登上世界舞台。
3.从属连语的用法
连接状语从句的连词只起连接主句与从句的作用，在从句中不充当句子成分：
When he comes back, tell him to call me.
在他回来时，叫他打电话给我。
Nobody will feel pleased if you try to please everyone.
如果你想讨好每一个人，一个也讨好不了。
The students started their preparation one month in advance so that they could pass the test easily.
学生们提前一个月进行准备，以便能轻松过关。
She talked asif she were still a child.
她说话的样子好像还是个小孩。
连接主语、表语、宾语从句的连词(除that, if, whether外)有两重作用：既连接主句与从句，标志从句的开始，又在从句中充当一个句子成分。
Who did it is still not known.
谁干的还不知道。
(who既连接主句和主语从句，又在主语从句叫充当主语)
That is what they told me.
那是他们告诉你的话。
(what既连接主句和表语从句，又在从句叫当told的宾语)
说明：
1.that, if, whether是纯连词，只起连接作用，不能在从句中充当句子成分。
2.连接主语、表语、宾语从句的连词(除that,if, whether外)往往含有两个(以上)单词的意思和作用，相当于“先行词+关系词”：
What she gave me is a secret.
她给我的东西是个秘密。
(what=the thing which)
That is why we get along with well.
那就是我们相处很好的原因。
(why=the reason why)
I know where he was born.
我知道他在哪里出生的。
(where=the place where，但由于where比the place where简单清爽，人们便喜欢用where)
注意：
中国学生常常只会用一些状语从句和宾语从句，不会用主语从句、表语从句和定语从句。所以，需要自觉地专门集中造几十个带有主语多句、表语从句和定语从句的句子，以此强化印象，培养习惯。
