十五、復合句——副詞性(狀語)從句
副詞在句中起狀語作用，故如果起狀語作用的部分為一個句子，那么該句便是副詞性從句，也稱狀語從句。狀語從句可細分為：時間、地點、條件、原因、讓步、目的、結果、比較、方式等。
狀語從句的測試重點為：考查考生對主從句之間邏輯意義關系的把握，看其是否能選擇正確的從屬連詞。
1.條件狀語從句的常考知識點
(1)if與unless的用法。
if和unless都是引導條件狀語從句的連詞，考生應尤其注意unless的用法，因為它表示反面條件，相當于if not“如果不”、“除非”。如：
In debating, one must correct the opponent’s facts, deny the relevance of his proof, or deny that what he presents as proof, if relevant, is sufficient.
(2)復合連詞as long as，so long as，as far as，on condition that，in the event that;動詞及分詞provided(that)，providing(that)，given that, suppose/supposing(that)，assuming，say等引導條件狀語從句。如：
You can arrive in Beijing earlier for the meeting provided you don’t mind taking the night train.
Assuming he is diligent in his studies at ordinary times, he is sure to pass the test.
In the event that she has not been informed, I will tell her. (如果……)
You can go swimming on condition that you don’t go too far from the river bank. (如果……)
Suppose it rained, we would still go. (假如……)
Say it were true, what would you do about it? (假如……)
(3)祈使句表示條件。如：Dress warmly, or else you’ll catch cold.
Talk to anyone in the drug industry, and you’ll soon discover that the science of genetics is the biggest thing to hit drug research since penicillin was discovered.
2.讓步狀語從句的常考知識點
(1)as 引導讓步從句，要求用倒裝結構，把強調的部分置于句首。如：
Much as he likes her, he does get irritated with her sometimes.
Humble as it may be, there is no place like home.
(2)while引導讓步從句。如:
Everybody cheats a little, some psychologists say, while others insist that most people are basically honest and some wouldn’t cheat under any circumstances.
(3)復合連接詞for all that和分詞granting/granted(that)引導讓步從句。如:
Granted you have made much progress, you should not be conceited.
For all that computers can provide us with great help, they shouldn’t be seen as substitutes for fundamental thinking and reasoning skills.
3.時間狀語從句的常考知識點
(1)before表示漢語的 “只有/必須……才能”。如:
New ideas sometimes have to wait for years before they are fully accepted.
(2)when引導時間從句時，如果出現在后半句，則表示“這/那時突然”。如：
I have just started back for the house to change my clothes when I heard the voices.
(3)when it comes to 是習慣用法，意為“當談到……時”。如：
Doing your homework is a sure way to improve your test scores, and this is especially true when it comes to classroom tests.
(4)名詞短語、介詞短語each /every time, the moment/second/minute, in the time, by the time起連詞作用。如:
I hope her health will have improved greatly by the time we come back next year.
My pain must have been apparent the moment I walked into the room, for the first man I met asked sympathetically: “Are you feeling all right?”
Mercury’s velocity is so much greater than the Earth’s that it completes more than four revolutions around the Sun in the time it takes the Earth to complete one.
(5)副詞directly, immediately, instantly, now引導時間從句, 相當于as soon as。如:
The policemen went into action directly they heard the alarm.
