问题补充:
As it turned out to be a small house party, we so formally.
A. needn’t dress up
B. didn’t have to dress up
C. might not have dressed up
D. needn’t have dressed up
答案:
A. needn’t dress up
B. didn’t have to dress up
C. might not have dressed up
(答案→)D. needn’t have dressed up
解析:根据前一句说这是一个小型的家庭聚会,所以后一句意思是:本没必要,故选D。