2012考研必备：考研英语语法精要(45)
1.条件状语从句的常考知识点(1)if与unless的用法。
if和unless都是引导条件状语从句的连词，考生应尤其注意unless的用法，因为它表示反面条件，相当于if not“如果不”、“除非”。如：
Even if automakers modify commercially produced cars to run on alternative fuels, the cars won’t catch on in a big way unless drivers can fill them up at the gas station.
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)复合连词as long as，so long as，as far as，on condition that，in the event that；动词及分词provided(that)，providing(that)，given that, suppose/supposing(that)，assuming，say等引导条件状语从句。如：
If left alone by humans, they (the forests) can regenerate, as long as there are seed trees in the neighborhood and the soil has not lost all its nutrients.
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)祈使句表示条件。如：
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.
Dress warmly, or else you’ll catch cold.
Hurry up, or the tickets will have been sold out by the time we get there.
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