大学体验英语(二)

General Writing: Unreal Conditions

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To make predictions, you may find unreal conditional clauses useful. Unreal conditions are either impossible to realize or unlikely to be realized. In these sentences, a contrary-to-fact condition exists.
Examples:
　　Present Time:
　　　　If this was allowed to happen, the dam would collapse.
　　　　If the dam collapsed, many acres of good farmland would disappear.

　　Past Time:
　　　　If this had not been allowed to happen, the dam would not have collapsed.

　　Past Time with Present or Future Result:
　　　　If they had passed the law, the economy would be in better shape now.

1. Complete the sentences with the appropriate verb form.
　　Example: If the weather is warm, I will go swimming.
　　　　　　　If the weather were warm, I would go swimming.
　　　　　　　If the weather had been warm, I would have gone swimming.

1) If I have time, I will write some letters.
　　If I had time, I some letters.
　　If I had had time, I some letters.
2) If he makes an appointment, he can see the director.
　　If he made an appointment, he the director.
　　If he had made an appointment, he the director.
3) If I slip on the ice, I may break my leg.
　　If I slipped on the ice, I my leg.
　　If had slipped on the ice, I my leg.
4) I will lock the door if you give me a key.
　　I would lock the door if you me a key.
　　I would have locked the door if you me a key.
5) We can go on a picnic if the weather is nice.
　　We could go on a picnic if the weather nice.
　　We could have gone on a picnic if the weather nice.

Anwser: 1. would write; would have written 　2. could see; could have seen　3. might break; might have broken
　　　　4. gave, had given　　5. were, had been