【第一篇：條件狀語從句】
■引導(dǎo)條件狀語從句的從屬連詞
主要的有if, unless, as [so] long as等：
You can leave now if you like. 如果你愿意現(xiàn)在就可以走了。
As long as it doesn’t rain we can go. 只要不下雨，我們就可以去。
【注】除以上基本的引導(dǎo)條件狀語從句的從屬連詞外，還有的動(dòng)詞尤其是其分詞形式(如suppose, supposing, provided, providing等)和介詞短語(如in case, on condition that等)也可用作連詞表示條件：
In case I forget, please remind me about it. 萬一我忘記，請(qǐng)?zhí)嵝盐乙幌隆?/p>
I will come on condition (that) she is invited too. 如果邀請(qǐng)她來, 那我就來。
He may go with us provided [providing] he arrives in time. 他若及時(shí)到，就可以和我們一起走。
Suppose 和supposing 引導(dǎo)條件狀語從句時(shí)，通常用于主句為疑問句的場(chǎng)合：
Suppose the boss saw you，what would he say? 如果老板看到你，他會(huì)怎樣說?
Supposing he does not come, shall we go without him? 他若不來，是不是不帶他去?
■條件狀語從句的時(shí)態(tài)
當(dāng)主句為將來時(shí)態(tài)或具有將來意時(shí)，條件狀語從句通常要用一般現(xiàn)在時(shí)表示將來意義，而不能直接使用將來時(shí)態(tài)：
I’ll stay at home if it rains tomorrow. 要是明天下雨，我就呆在家里。
【注】有時(shí)也可見到 if you will 這樣的說法，但那不是將來時(shí)態(tài)，而是表示意愿或委婉的請(qǐng)求(此處的 will是情態(tài)動(dòng)詞)：
If you will wait for a moment, I’ll go and tell the manager that you are here. 請(qǐng)等一下，我去告訴經(jīng)理說你來了。
【第二篇：時(shí)間狀語從句】
■引導(dǎo)時(shí)間狀語從句的從屬連詞
引導(dǎo)時(shí)間狀語從句的從屬連詞很多，如較基本的有before, after, when, while, as, since, till, until, as soon as 等：
Things were different when I was a child. 我小時(shí)候情況與現(xiàn)在不同。
We must strike while the iron is hot. 我們要趁熱打鐵。
It’s a long time since I met you last. 從上次見到你，已有很長時(shí)間了。
He waited until she was about to leave. 他等著一直到她準(zhǔn)備離開。
除以上基本的引導(dǎo)時(shí)間狀語從句的從屬連詞外，還有些本來不是從屬連詞卻可用作從屬連詞的詞：
(1) 表示“一…就”的從屬連詞：the moment, the minute, the second, the instant, immediately, directly, instantly, once, no sooner…than, hardly…when等。如：
Immediately he came I told him the news. 他一來我就把消息告訴了他。
The moment I saw him I knew there was no hope. 我一看到他就知道沒希望了。
We had no sooner set out than it began to rain. 我們剛出發(fā)就下雨了。
Once he arrives, we can start. 他一來我們就可以開始。
(2) 涉及time的幾個(gè)從屬連詞：every time(每次)，each time(每次)，(the) next time(下次)，any time(隨時(shí))，the last time(上次)，the first time(第一次)。如：
Every time I see her I’ll think of it. 每次我看到她，我就想起這事。
He felt nervous each time she spoke to him. 每次她和他講話，他都感到緊張。
He didn’t tell me the last time I saw him. 我上次見到他時(shí)他沒告訴我。
■與時(shí)間狀語從句有關(guān)的時(shí)態(tài)問題
關(guān)于這個(gè)問題有兩點(diǎn)值得注意：
(1) 當(dāng)主句為將來時(shí)態(tài)或具有將來意義時(shí)，時(shí)間狀語從句通常要用一般現(xiàn)在時(shí)表示將來意義，而不能直接使用將來時(shí)態(tài)：
Turn off the lights before you leave. 走前關(guān)燈。
I will tell him as soon as he arrives. 他一來我就告訴他。
(2) 與since 從句搭配的主句的時(shí)態(tài)通常是現(xiàn)在完成時(shí)態(tài)：
He has lived here since 1999. 自1999年以來，他就一直住在這兒。
Where have you been since I last saw you? 自我上次見到你之后你到哪里去了?
【注】在特定的語言環(huán)境中有時(shí)也可能用過去完成時(shí)或一般現(xiàn)在時(shí)：
It seems like years since we last met. 我們似乎幾年未見面了。
Yesterday he told me that he hadn’t eaten anything since Tuesday. 他昨天告訴我自星期二以來他一直未吃任何東西。
【第三篇：目的狀語從句】
■引導(dǎo)目的狀語從句的從屬連詞
主要的有 in order that, so that, in case, for fear等：
Speak clearly so that they may understand you. 講清楚些，以便他們能理解你。
He studied hard in order that he could pass the exam. 他努力學(xué)習(xí)以便能考試及格。
Shut the window for fear that it may rain. 把窗子關(guān)上以防下雨。
【注】so that 引導(dǎo)目的狀語從句時(shí)有時(shí)可省略so而只用that，有時(shí)也可只用so：
Bring it closer that I might see it better. 拿近些，使我能看得清楚些。
I’ll show you so you can see how it’s done. 我將做給你看，以便你知道應(yīng)怎樣干。
■目的狀語從句與狀語短語的轉(zhuǎn)換
為了簡潔起見，當(dāng)目的狀語從句的主語與主句的主語相同時(shí)，目的狀語從句有時(shí)可用表目的的不定式短語替換：
He got up early so that he could catch the early bus. / He got up early so as to catch the early bus. 他起床很早以便趕上早班車。
He came in quietly in order that he shouldn’t wake his wife. / He came in quietly in order not to wake his wife. 他輕輕進(jìn)來，以免把他妻子吵醒。
有時(shí)還可與表示目的的介詞短語替換(from www.yygrammar.com)：
He left an hour early for fear he might miss the train. / He left an hour early for fear of missing the train. 他提前一小時(shí)離開，以免錯(cuò)過火車。
■一點(diǎn)注意
in case既可引導(dǎo)目的狀語從句，也可引導(dǎo)條件狀語從句，主要視句意而定：
In case he comes, let me know. 如果他來，告訴我一聲。
Tell me in case you get into difficulty. 遇到困難請(qǐng)告訴我。
【注】in case引導(dǎo)目的狀語從句，從句有時(shí)可用“should+動(dòng)詞原形”這樣的形式：
Take your coat in case it rains (should rain). 帶著雨衣以防下雨。
