I hurried to the post office ,__ it was closeda、only to be found b、only to finding c、only to have been found d、only to find 为什么正确答案是b?

问题描述:

I hurried to the post office ,__ it was closed
a、only to be found
b、only to finding
c、only to have been found
d、only to find
为什么正确答案是b?

c、only to have been found

正确答案错了,应该是d
only to do sth.表示意料之外发生的事,前面要加逗号