1、主句謂語(yǔ)動(dòng)詞為現(xiàn)在時(shí)態(tài)，則從句動(dòng)詞可根據(jù)需要使用任何時(shí)態(tài)；主句謂語(yǔ)動(dòng)詞為過(guò)去時(shí)態(tài)，從句的時(shí)態(tài)一般是過(guò)去范疇的時(shí)態(tài)，其中有如下幾種 情況要注意：1. 當(dāng)從句的動(dòng)作與主句的動(dòng)作同時(shí)發(fā)生，從句中一般用一般過(guò)去時(shí)或過(guò)去進(jìn)行 時(shí)。2. 從句的動(dòng)作發(fā)生在主句動(dòng)作之后，從句時(shí)態(tài)用過(guò)去將來(lái)時(shí)。3. 從句的動(dòng)作發(fā)生在主句動(dòng)作之前，從句時(shí)態(tài)用過(guò)去完成時(shí)。主將從現(xiàn)原則在if，uni ess等詞引導(dǎo)的條件狀語(yǔ)從句;在 when，till/until，as soon as before，after，as, while，each time, the moment 等詞引導(dǎo)的時(shí)間狀語(yǔ)從句；在 no matter + wh-

2、，however，whatever，whenever，even if/even though, so long as, on condition that等引導(dǎo)的讓步狀語(yǔ)從句 中，若主句為一般將來(lái)時(shí)（或包含情態(tài)動(dòng)詞/祈使句），從句謂語(yǔ)動(dòng)詞常用一般現(xiàn) 在時(shí)表示將來(lái)；若主句為過(guò)去將來(lái)時(shí)，從句謂語(yǔ)動(dòng)詞通常用一般過(guò)去時(shí)態(tài)代替過(guò)去將來(lái)時(shí)態(tài)。e.g. I will call you as soon as she arrives.當(dāng)她來(lái)的時(shí)候，我就打電話(huà)給你。If it clears up, we will go to the park.如果天晴的話(huà)，我們就去公園。I will not let them i

3、n, whoever they are.不管他們是誰(shuí)，我都不會(huì)讓他們進(jìn)來(lái)。（2008 全國(guó)U, 14）If their marketing plans succeed, theytheir sales by 20 percent.A. will in crease B. have bee n in creas ing C. have in creased D. would be in creas ing特定引導(dǎo)詞及句式的時(shí)態(tài)I . sincesince引導(dǎo)的時(shí)間狀語(yǔ) 從句為一般過(guò)去時(shí)，主句中的時(shí)態(tài)用現(xiàn)在完成時(shí)或現(xiàn)在 完成進(jìn)行時(shí)。e.g. Jenny has had ano ther babsi

4、 nee I saw her last.從上次我見(jiàn)到Jenny以來(lái)，她又生了一個(gè)孩子。I have bee n lear ning En glishs ince I was in Grade 3.自從上三年級(jí)以來(lái)，我一直在學(xué)英語(yǔ)。The girl told her father she had bee n ills ince she came home.那個(gè)女孩告訴她父親，自從回到家她就一直在生病。Note: It + be + 一段時(shí)間+ since 中，若主句為一般現(xiàn)在時(shí)或現(xiàn)在完成時(shí)，從 句常用一般過(guò)去時(shí)；如果主句為一般過(guò)去時(shí)，從句則常用過(guò)去完成時(shí)。e.g. It is more tha

5、n three years nominee I saw her last.自此我上次見(jiàn)到她，我們已有三年多沒(méi)見(jiàn)面了。It has been three yearsince I was in Beijing.我不在北京已經(jīng)三年了。(1988全國(guó))They asked me to have a drink with them. I said that it was at least ten years since I a good drink.A. had enjo yedB. was enjoying C. enjo yedD. had bee n enjoyingn. beforebefore

6、引導(dǎo)的時(shí)間狀語(yǔ) 從句若是過(guò)去時(shí)，主句可用一般過(guò)去時(shí)或過(guò)去完成時(shí)。e.g. He closed the doorbefore he left the classroom.他在離開(kāi)教室之前關(guān)上了門(mén)。We had bee n to four citiesbefore he came to join us.他來(lái)加入我們之前我們已經(jīng)去了四個(gè)城市了。Note: before的常用句型It will (wo nt) be + 時(shí)間段 / lo ng + before + 一般現(xiàn)在時(shí)It was （was nt） + 時(shí)間段 /Io ng + before + 一般過(guò)去時(shí)（2008 北京，34）Im sorr

7、y youve been waiting so long, but itll still be some timeBrian getsback.A. before B. since C. tillD. after川.by the timeby the time指到某一點(diǎn)時(shí)間為止，主句 常用完成時(shí)態(tài)。一般情況下，如果 從 句表示的是過(guò)去時(shí)間，主句常用過(guò)去完成時(shí)；如果從句表示的是將來(lái)時(shí)間， 主句則常用將來(lái)完成時(shí)。e.g. By the time you come here tomorrow, will have fini shed this work.你明天來(lái)這兒的時(shí)候，我將已經(jīng)完成此工作了。By

8、 the time he was 15he had travelled to more tha n 12 coun tries.到15歲為止，他已經(jīng)去過(guò)12個(gè)國(guó)家了。By the time he went abroad he was 15. 他出國(guó)那年15歲。（2002上海）He will have lear ned En glish for eight years by the time hefrom the uni versityn ext year.A. will graduate B. will have graduated C. graduates D. is to graduateiv.no sooner. than ，hardly / scarcely / barely when引導(dǎo)的時(shí)間狀語(yǔ)從句，其 主句通常用過(guò)去完成時(shí)，從句通常用一般過(guò)去時(shí)。e.g. Hardly had he arrivedwhe n she started complai ni