Would be able finish his home work,he would have come to class.

问题描述:

Would be able finish his home work,he would have come to class.
请问为什么前一句用would?
if从句中如果有should,had或were,不是省略if,把这些词放在句首么?

应该是虚拟语气的用法.
不过这句话有点奇怪,你没打错吧