語法復(fù)習(xí)六：狀語從句
由從句擔(dān)任的狀語，在句子中可修飾謂語（或其它動詞）、形容詞、副詞或是整個句子，它可以用來表示時間、地點(diǎn)、原因、目的、結(jié)果、條件、方式、比較、讓步等。狀語從句是一較大的語法項(xiàng)目，也是近幾年高考題中常見的一個重要試點(diǎn)。高考中已考查了時間、讓步、地點(diǎn)、條件、目的等狀語從句，這些從句仍是今后高考熱點(diǎn)，應(yīng)作充分準(zhǔn)備。同時對方式狀語從句也應(yīng)引起重視。
（一）時間狀語從句
表示時間的狀語從句可由when, as, while, whenever, after, before, till (until), since, once, as soon as (或the moment ), by the time, no sooner … than, hardly (scarcely) … when, every time等引導(dǎo)。
e.g. when i came into the office, the teachers were having a meeting.
he started as soon as he received the news.
once you see him, you will never forget him.
no sooner had i gone to bed than i went to sleep.
（二）原因狀語從句
原因狀語從句是表示原因或理由的，引導(dǎo)這類從句的最常用的連詞是because, since, as , now that（既然）等，for 表示因果關(guān)系時（它引導(dǎo)的不是從句）為并列連詞，語氣不如because強(qiáng)。
e.g. he is disappointed because he didn't get the position.
as it is raining, i will not go out.
now that you mention it, i do remember.
（三）地點(diǎn)狀語從句
引導(dǎo)地點(diǎn)狀語從句的連詞是where 和wherever等。
e.g. sit wherever you like.
make a mark where you have a question.
（四）目的狀語從句
引導(dǎo)目的狀語從句最常用的詞（組）是so, so that（從句謂語常有情態(tài)動詞）, in order that, in case（以防，以免）等。
e.g. speak clearly, so that they may understand you.
she has bought the book in order that she could follow the tv lessons.
he left early in case he should miss the train.
（五）結(jié)果狀語從句
結(jié)果狀語從句是表示事態(tài)結(jié)果的從句，通常主句是原因，從句是結(jié)果。由so that （從句謂語一般沒有情態(tài)動詞）, so … that, such … that等引導(dǎo)。
e.g. she was ill, so that she didn’t attend the meeting.
he was so excited that he could not say a word.
she is such a good teacher that everyone admires her.
（六）條件狀語從句
條件狀語從句分真實(shí)性（有可能實(shí)現(xiàn)的事情）與非真實(shí)性（條件與事實(shí)相反或者在說話者看來不大可能實(shí)現(xiàn)的事情）條件句。引導(dǎo)條件狀語從句的詞（組）主要有if, unless, so (as) long as, on condition that, so (as) far as, if only ( = if )。注意：條件從句中的if 不能用whether替換。
e.g. if he is not in the office, he must be out for lunch.
you may borrow the book so long as you keep it clean.
so far as i know（據(jù)我所知）, he will be away for three months.
you can go swimming on condition that ( = if ) you don’t go too far away from the river bank.