Unit21 Human Biology-语法篇

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1、掌握混合条件句中的虚拟语气的用法。

2、情态动词的用法。

混合条件句中的虚拟语气

　　混合条件句主句是指条件句中含有不同的条件结构，谓语动词所表示的动作和条件从句谓语动词所表示的动作并不是同时发生,如一个与过去事实相反，另一个与现在事实相反。在这种条件句中， 动词的形式要根据具体情况进行调整。

非真空条件从句 主句 If it had rained last night, it would be very cold today. If I had taken your advice, I would have no trouble with the work now. If I were you, I would have gone to see the film last night. If he had told me about it, I would known what to do now If you had followed the doctor's advice (then), you would be all right now.

如果你那时听了医生的话,你现在就好了.

(主句与从句发生的时间不同,应按照主句与从句各自的时间做调整.)

If you had watered them more, the crops would be growing still better.

如果你再给庄稼多浇些水,他们会长得更好.

(指现在长得更好.)

If you had watered them more, the crops would have grown still better.