had he been here yesterday,he would attend.为什么是had了,后面是would do而不是would have done

had he been here yesterday,he would attend.为什么是had了,后面是would do而不是would have done
had he been here yesterday,he would attend.
为什么是had了,后面是would do而不是would have done

had he been here yesterday,he would attend.为什么是had了,后面是would do而不是would have done
这个是错综时间虚拟语气条件句,先说倒装,当虚拟语气的条件句用到had done(对过去）或were（对现在或将来）或should（对将来）时要省略if,把前面的三种情况的任何一种置于句首倒装,你的句子实际是：If he had been here yesterday倒装之后就变成你所写的了,而错综时间是主句的所要表达的时间和从句所要表达的时间不同时,就会产生了,你的句子要表达的是如果过去他怎么样,他现在就会怎么样,所以主句应该要用对现在的虚拟would/should/might/could +V动词原形