老师上课时说过，but后用陈述语气，but前用虚拟语气，那么具体怎么用呢？我指的是but前的虚拟语气，是用should do还是had done或是其他？请举例，谢谢！
提供两个句子：1.Did you go to see him yesterday? I would have,but my cousin dropped by to see my new house. 2.I had meant to call you last night but was prevented by the storm. 这两个句子中，but前的虚拟方式为什么不一样？
这个but的虚拟的时态和我们平时虚拟的时态是一样的，没有什么不同。只是跟的句子是以前我们的if 条件状语从句的后半句
比如：
I would have had a better job, but I didn't work hard on study.（过去的虚拟）
I would fly, but I am not a bird.(现在的虚拟)
I would be very happy, but I am not going to get the prize.(将来的虚拟)
所以根据时间的不同but前面的句子分别是would have done, would do, would do,而后面的句子就是正常的过去式，现在时和将来时
比如：
I would have had a better job, but I didn't work hard on study.（过去的虚拟）
I would fly, but I am not a bird.(现在的虚拟)
I would be very happy, but I am not going to get the prize.(将来的虚拟)
所以根据时间的不同but前面的句子分别是would have done, would do, would do,而后面的句子就是正常的过去式，现在时和将来时
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第1个回答 2010-02-24
1.Did you go to see him yesterday? I would have,but my cousin dropped by to see my new house.
暗含条件句，与过去事实相反的假设， I would have 是主句
还原一下：if my cousin hadn't dropped by to see my new house,I would have gone to see him .
2.I had meant to call you last night but was prevented by the storm.
had meant to 是条件从句的简化与省略
在实际运用过程中，条件从句经常简化为一个短语或一个单词，甚至省略。
例1. But for his help, we would not have succeeded.
→ If it had not been for his help, we would not have succeeded.
例2. Without your help, we could not have finished the work ahead of time.
→ If it had not been for your help, we could not have finished the work ahead of time.
△ 注意would/should/could/might都有具体的含义，例should表示应该，could表示能够，might表示可以；should have done本应该；could have done本能够； might have done本可以。
① should have done本应该; could have done本能够;
本… might have done 本可以 needn’t have done 本不必
② did / had done
( hoped /had hoped 本希望; thought / had thought 原以为；intended / had intended 本打算；wanted /had wanted 本想； planned/ had planned 原计划；meant / had meant 本意)
例：His father had hoped that his son would go to business with him, but his son became an artist later.
I thought you didn’t come here. I’m really glad to see you here.
暗含条件句，与过去事实相反的假设， I would have 是主句
还原一下：if my cousin hadn't dropped by to see my new house,I would have gone to see him .
2.I had meant to call you last night but was prevented by the storm.
had meant to 是条件从句的简化与省略
在实际运用过程中，条件从句经常简化为一个短语或一个单词，甚至省略。
例1. But for his help, we would not have succeeded.
→ If it had not been for his help, we would not have succeeded.
例2. Without your help, we could not have finished the work ahead of time.
→ If it had not been for your help, we could not have finished the work ahead of time.
△ 注意would/should/could/might都有具体的含义，例should表示应该，could表示能够，might表示可以；should have done本应该；could have done本能够； might have done本可以。
① should have done本应该; could have done本能够;
本… might have done 本可以 needn’t have done 本不必
② did / had done
( hoped /had hoped 本希望; thought / had thought 原以为；intended / had intended 本打算；wanted /had wanted 本想； planned/ had planned 原计划；meant / had meant 本意)
例：His father had hoped that his son would go to business with him, but his son became an artist later.
I thought you didn’t come here. I’m really glad to see you here.
