英語語法：連詞的用法和從屬連詞
連詞：連接單詞與單詞、詞組與詞組、句子與句子、從句與主句的詞叫連詞。
連詞也是虛詞，不能獨立作句子成分。
連詞分爲並列連詞和從屬連詞兩種，並列連詞用於連接兩個或者兩個以上並排列舉的單詞、詞組或者句子，從屬連詞用於連接從句和主句。
1.連接狀語的連詞最多
表時間：
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.
那麼在那以前呢?在那以前，甚至太陽，我們可愛又古老的太陽也不存在。
Nike didn’twait until dinnertime until they sent out a press release saying they were suspending the relationship.
耐克在晚餐前便發佈新聞稿表示將暫停和莎拉波娃的合同。
表條件：
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!
我們只要有一些填料，就可以煮了這個小老鼠。
You may keep the book a further week provided that no one else requires it.
倘若這本書沒有其他人想借的話，你可以續借一個星期。
表讓步：
though, although
even if, even though
though the buyer ended up stiffing him for half of that.
但是最後買家只給了一半的錢。
No fans will be permitted into the game even ifthey bought tickets.
即使買了門票，粉絲們也不能進去。
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.
我將會像是很痛苦的樣子……我有點像要死去似的。
He said it’s as if the crew played a computer game.
2.連接主語從句、表語從句和賓語從句的連詞
純連詞：
that, whether, if(注：if不能用於主語從句)
It is surprised for me that my father has much money.
使我驚訝的是，我爸有許多錢。
連接副詞：
when, where, how, why
Work hard when youare at work and have a good rest when you are free.
工作時努力工作，休息時好好休息。
That is why Ican’t catch the train.
那就是我沒有趕上這班火車的原因。
連接代詞：
what, which, who, whose
What will matter is not what you learned, butwhat you taught.
重要的不是你所學的而是你所授的。
It is superpower-in-waiting whose people vote,whose society is raucous, and whose firms are red-blooded and striding onto the world stage.
印度正在成長爲一個超級大國，民衆擁有選舉權、社會充滿活力、商業蓬勃發展大步登上世界舞臺。
3.從屬連語的用法
連接狀語從句的連詞只起連接主句與從句的作用，在從句中不充當句子成分：
When he comes back, tell him to call me.
在他回來時，叫他打電話給我。
Nobody will feel pleased if you try to please everyone.
如果你想討好每一個人，一個也討好不了。
The students started their preparation one month in advance so that they could pass the test easily.
學生們提前一個月進行準備，以便能輕鬆過關。
She talked asif she were still a child.
她說話的樣子好像還是個小孩。
連接主語、表語、賓語從句的連詞(除that, if, whether外)有兩重作用：既連接主句與從句，標誌從句的開始，又在從句中充當一個句子成分。
Who did it is still not known.
誰幹的還不知道。
(who既連接主句和主語從句，又在主語從句叫充當主語)
That is what they told me.
那是他們告訴你的話。
(what既連接主句和表語從句，又在從句叫當told的賓語)
說明：
1.that, if, whether是純連詞，只起連接作用，不能在從句中充當句子成分。
2.連接主語、表語、賓語從句的連詞(除that,if, whether外)往往含有兩個(以上)單詞的意思和作用，相當於“先行詞+關係詞”：
What she gave me is a secret.
她給我的東西是個祕密。
(what=the thing which)
That is why we get along with well.
那就是我們相處很好的原因。
(why=the reason why)
I know where he was born.
我知道他在哪裏出生的。
(where=the place where，但由於where比the place where簡單清爽，人們便喜歡用where)
注意：
中國學生常常只會用一些狀語從句和賓語從句，不會用主語從句、表語從句和定語從句。所以，需要自覺地專門集中造幾十個帶有主語多句、表語從句和定語從句的句子，以此強化印象，培養習慣。
