这个是我们讲的虚拟语气的用法,在虚拟语气中,与将来时态的虚拟有三种都是在if条件句中：
if+过去式+其它
if+should+do+其它
if+were to+其它
看看,因为只有在虚拟语气中才会有should+do”可以换成过去式的用法.If you succeeded, everything would be all right.If you should succeed, everything would be all right.If you were to succeed, everything would be all right.这三个是不是个很好的例子？对，太棒了。