问题
单项选择题
As it turned out to be a small house party, we （） so formally.
A．needn't dress up
B．did not need have dressed up
C．did not need dress up
D．needn't have dressed up
答案
参考答案：D
解析：
needn't have done对过去发生事情的虚拟，表“本不必要，但实际上却”之意。