I don't know whether you happen to have heard,but I'm going to study in the USA this September.
问题描述：
I don't know whether you happen to have heard,but I'm going to study in the USA this September.
我一直在纠结一个问题 为什么这里要说you happen to have heard 而不是 you have happened to hear?
答
动词不定式的完成式,表示在谓语动词之前发生的动作,比如：To have known her is a privilege.This house seems to have been built by a very good architect.By 1992,he hoped to have opened a branch overseas.Th...碰巧和听说为什么有时间先后呢？应该是同时发生啊？一般来说，happen表示“碰巧”是不用现在完成时的，但是“听说”是说这句话之前就已经发生的，动词不定式必须用完成式形式，希望我能帮助你解疑释惑。那是不是hear不是在跟happen比较，而是在跟don't know之间比较时间先后？ 这么理解对吗对，可以这样理解，希望我能帮助你解疑释惑。