【英语语法】if引导的条件状语从句

1. if引导的条件状语从句

(1)真实条件句

If an advertisement conveys information which is false or misleading，the advertiser is committing an offence.

【译文】如果广告传递的信息是虚假的或误导性的，那么广告商的行为就是违法行为。

If they wanted to go out，they could always count on me to stay with the baby.

【译文】如果他们想外出，他们总是可以来找我看护他们的孩子。

The world will be destroyed if nuclear weapons are employed in a world war.

【译文】如果核武器今后用于世界大战，整个世界将被毁灭。 

注意：在条件状语从句中，如果动作是将来时间段发生的，通常用动词的一般现在时来表不。

(2)虚拟条件句

If I were a bird，I would fly to you.

【译文】如果我是只小鸟，我将飞向你的身旁。（发生在现在时间段）

I would have succeeded in finishing the experiment if I had accepted your advice.

【译文】如果我接受了您的建议，早就成功地完成这个试验了。（发生在过去时间段）

If he were to give me a ring，what should I answer?

【译文】假如他打电话给我，我该怎样回答？（将来时间段）

2.unless引导的否定性条件状语从句（=if not，常用于主句是否定的情形中）

He never says a word unless he feels he，s being threatened in some way.

【译文】除非感觉自己在某方面受到了威胁，否则他是不吱声的。

I'll not give you any money unless you return it next week.

【译文】我不会借一分钱给你，除非下周你还我。

3.provided(that)，as long as/so long as 和 only if 引导的条件状语从句

You may keep the book a further week provided(that )no one else requires it.

【译文】倘若这本书没有其他人想借的话，你可以再续借一个礼拜。

So long as/As long as there is something to identify，we will give people their money back.

【译文】只要可以确认，我们就可以把钱还给他们。

The picnic will be cancelled only if it rains.

【译文】只有在下雨的情况下，野餐才会取消。

Only if a teacher has given permission a student is allowed to enter this room.

【译文】只有得到老师的许可，学生才可以进这间办公室。

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