状语从句
　　状语从句：两个独立的句子中间用一些含义不同的连接词连接；状语从句用来表达两个句子之间的逻辑关系；分成原因状语、条件状语、结果状语、时间状语、地点状语、让步状语、目的状语、比较状语、方式状语等九大类型；
　　eg：I got up late.
　　I was late for school.
　　Because I got up late, I was late for school. （原因状语从句）
　　I got up late，so I was late for school. （结果状语从句）
　　地点状语：
　　地点状语从句通常由where，wherever，everywhere 引导；
　　eg：Where I live there are plenty of trees.
　　Wherever you work, you will gain much valuable experience as long as you are willing to work.
　　Wherever=no matter where
　　Everywhere they went, they were warmly received.
　　Where there is a will, there is a way.
　　where：不能翻译成在……地方时，通常翻译为如果，表示在……条件下；
　　eg: Where you are confident，you will succeed.
　　eg：Where previously the bank had concentrated on the big infrastructure projects , such as dams, roads and bridges，it begin to switch to projects which directly improved the basic services of a country.
　　concentrated on ：集中于……
　　方式状语从句：
　　方式状语从句通常由as，as if，as though，the way，what引导；
　　eg：Always do to the others as you would be done by.
　　When enter rome do as the romans do.
　　（1）as从句带有比喻的含义，意思是"正如…"，"就像"；
　　（2）as if/though："仿佛……似的"，"好像……似的"；
　　有时用虚拟语气，有时不用；
　　eg：They completely ignore these facts as if (as though) they never existed. （与事实相反，谓语用虚拟语气。）
　　He looks as if (as though) he had been hit by lighting.
　　（与事实相反，谓语用虚拟语气。）
　　It looks as if the weather may pick up very soon.
　　（实现的可能性较大，谓语用陈述语气。）
　　（3）the way：可以连接两个句子，表达就像……一样；
　　eg：I should do the job the way my father did.
　　Many Europeans now apparently view the US. the way many Americans view Mexican as a cheap place to vacation, shop and party.
　　（4）what：就像，犹如；
　　eg：Air is to man what/as water is to fish.
　　句型：A is to B what C is to D.
　　eg：A1 Gore calls global warming an "inconvenient truth," as if merely recognizing it could put us on a path to a solution.
　　put sb. on a path to a solution：找到解决的办法；
　　目的状语从句
　　可以由that, so that, in order that, lest, for fear that, in case等词引导；
　　lest：以防；从句中的谓语动词必须用should+动词原形；
　　eg: He wrote the name down for fear that(lest) he should forget it.
　　He took the umbrella with him lest it should rain.
　　in case：以防；与lest不同，从句里的时态不做特殊变化；
　　eg：Take the umbrella with you in case it rains.
　　for feat that：和lest保持一致；
　　eg：A variety of activities should be organized so that participants can remain active as long as they want and then go on to something else without feeling guilty and without letting the other participants down.
　　let…down…：让……感到气馁；
　　比较状语从句：
　　than, as…as…，not so as…，（not) the same as, the+比较级；
　　eg：Light travels fast than sound.
　　the+比较级：
　　eg：The sooner，the better.
　　eg：Girls are thus seen as less valuable than boys and art kept at home to do housework while their brothers are sent to school - the prophecy（预言) becomes self- fulfilling, trapping women in a vicious circle (恶性循环) of neglect.
　　（1）当……的时候：while, when, as ；
　　when：强调一件事情正在发生的时候，另外一件事情突然发生；
　　eg：When I was watching TV, my mother came back.
　　while：强调两个动作同时进行，一边……一边……；
　　eg：My father is cooking while my mother is reading newspaper.
　　as："随时间推移"
　　eg：As time went by, the days became longer and longer.
　　（2）一……就……：as soon as ,主将从现；用directly，immediately, instantly连接两个句子；一些名词如the minute，the moment, the instant也可表示；no sooner… than, hardly… when后面的句子需要倒装；
　　eg：I will write to you the moment/minute I arrived in Paris.
　　（3）特殊单词：by the time that, every/each time（使用时后面不要再加when）
　　（4）till＆until：
　　① 肯定形式表示的意思是"做某事直至某时"，动词必须是延续性的；
　　否定形式表达的意思是"直至某时才做某事"，一般用until，动词为延续性或非延续性都可以；
　　eg: I slept until midnight.
　　Wait till I call you.
　　She didn't arrive until 6 o'clock.
　　② Until可用于句首，而till通常不用于句首，通常用于句中；
　　eg: Until you told me, I had heard nothing of what happened.
　　eg：As you sleep you pass through a sequence of sleep states—light sleep, deep sleep and REM (rapid eye movement) sleep—that repeats approximately every 90 minutes.
　　结果状语从句
　　结果状语从句常由so… that 或 such…that引导；so保留，that可以省略；如此……以至于……；
　　eg：He didn't abide by the contract so that he was fined.
　　He was so excited that he couldn't fall asleep.
　　He made such an inspiring speech that everybody got excited.
　　比较：so和 such （1）so：so +形容词、副词+that；so+形容词+a/an+名词+that；
　　eg：The wind was so strong that we could hardly move forward.
　　He run so fast that I couldn't catch up with him.
　　It was so hot a day that crops wilted.
　　He is so lovely a boy that everyone loves him.
　　（2）such：such+a/an+形容词+名词+that
　　eg：It was such a hot day that crops wilted.
　　He is such a lovely boy that everyone loves him.
　　条件状语从句：
　　(1)连接词：if, once, as long as, on condition that
　　① 如果引导的条件可以实现，主将从现;
　　② 如果引导的条件和事实相反，则用虚拟语气;
　　eg：If winter comes can spring be far behind.
　　As long as it doesn't rain, we can play.
　　You can go out on condition that you wear an overcoat.
　　Modern cars are far tougher to steal, as their engine management computer won't allow them to start unless they receive a unique ID code beamed out by the ignition (点火) key.
　　原因状语从句
　　连接词：because, since, as, for ，now that, in that, owing to, due to, thanks to, because of , as a result of;
　　比较：because, since, as和for
　　1）because语势最强，用来说明人所不知的原因，回答why提出的问题。当原因是显而易见的或已为人们所知，就用as或 since。
　　I didn't go, because I was afraid.
　　Since /As the weather is so bad, we have to delay our journey.
　　2）由because引导的从句如果放在句末，且前面有逗 号，则可以用for来代替。但如果不是说明直接原因，而是多种情况加以推断，就只能用for。
　　He is absent today, because / for he is ill.
　　He must be ill, for he is absent today.
　　now that ：既然；
　　in that :因为，通常只能放在句中，强调重要的，唯一的的原因；
　　eg：Now that this semester is finished, I am going to rest a few days and take a trip.
　　Human beings are different from animals in that human can speak and think.
　　owing to, due to, thanks to, because of , as a result of等短语后面只能接词或短语，不能接从句；
　　让步状语从句
　　常见的连接词有though, although，as, while, even though
　　区分though，although，as
　　eg：Although/though he is a child, he can live by himself.
　　as 表示虽然的时候，要进行倒装；
　　Child as/though he is , he can live by himself.
　　eg：Although/though she works very hard ,she makes very little progress.
　　Hard as she works, she makes very little progress.
　　Although/though she is young, she has travelled to many countries to put shows .
　　Young as she is, she has travelled to many countries to put shows .
　　while：连接两个句子，表示虽然，但是；
　　eg：He is experienced while he is young.
　　真题分析：
　　1.The anti-virus agent was not known
　　(直到一名医生偶然发现了它)
　　until a doctor find it by chance.
　　2.I would prefer shopping online to shopping in a department store because __________（它更加方便和省时）
　　it is more convenient and timesaving.
　　3.But since water is much cheaper than wine, and many of the fancier brands aren’t available in stores, most diners don’t notice or care.
　　4. While there’s no question that continuous stress is harmful, several studies suggest that challenging situations in which you’re able to rise to the occasion can be good for you.