131. The Commerce Department announced that the economy grew during the second quarter at a 7.5 percent annual rate, while inflation eased when it might have been expected for it to rise.

(A) it might have been expected for it to rise

(B) it might have been expected to rise

(C) it might have been expected that it should rise

(D) its rise might have been expected

(E) there might have been an expectation it would rise

这题的正确答案是b我没有疑问，可是我明白的是为什么要用might have done 这样的结构，是虚拟语气吗？为什么要虚拟？请NN们指教啊！先谢了！！！

When you want to talk about something in the past, you can use may

have or might have:

A: I was suprise that Kate wasn't at the meeting yesterday.

B: She might not have known about it. (= perhaps she didn't know)

This is not 虚拟语气.