If you had practiced speaking English every day, you would speak English well enough. (从句说的是过去,主句指的是现在)
如果你当初每天都练习说英语的话,你的英语就会说得很好.
(有时假设的条件不通过条件句表达出来,而隐含在某些介词短语:如without,but for 等,或上下文,这中句子属于含蓄虚拟语气)
Without air, there would be no living things.
相当于:If there were no air, there would be no living things.
But for your help, I couldn’t have done it.
相当于:If you had not helped me, I couldn’t have done it.
如果条件状语从句的谓语中有were, had或should,就可以倒装。
将were, had或should放到句首,谓语主语之前, if去掉。
变为”were/had/should+主语”的形式。如果从句没有were, had或should,就不能倒装。
If I were to do it, I’d do it some other way.→ Were I to do it, I`d do it some other way.
If you should fail, try again.→ Should you fail, try again.
If you had been here earlier, you would have seen him.→ Had you been here earlier, you would have seen him.
If you came tomorrow, we would have the meeting.这句话不能倒装.
而且,在虚拟条件状语从句中,省略了if的倒装形式的句首不能用动词的缩略形式.如:
Were it not for the expense, I would go to Italy. 但不能说: Weren`t it for the expense, I would go to Italy.