第2个回答 2019-03-10
if后面是跟句子的,举例if做连词用于条件句中的用法。
a.If you study hard, you will pass the exam. 如果你努力学习,那么你就能通过这次考试。(真实条件)
b. If the boy should (或 were to) study hard, he would pass the exam. 假如这男孩果真努力学习,那么他就会通过这次考试。(句子含有“将来不大可能实现”的意味。)
I shall not go out if you come tomorrow. 如果你明天来,那我就不出去了。(这是真实条件。注意条件状语从句不用将来时态,要用现在时态来代替。在本情况下,主要靠主句谓语将来时态来判别。)
If I were not busy now, I should (或 would) go to the meeting. 要是我现在不忙,我就去开会了。(对现在事实相反的假设,谓语都用虚拟语气。也可用情态动词 could, might 代替 should, would 只是含义不同。)
If he had not been busy yesterday, he would have come to the trade fairs. 假如他昨天不忙,他早就来贸易展销会了。(对过去事实相反的假设,谓语都用虚拟语气。注意和上句表示形式不同。)