问题补充:
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 to dress up
D. needn’t have dressed up
答案:
A. needn’t dress up
B. did not need have dressed up
C. did not need to dress up
(答案→)D. needn’t have dressed up
解析:考查情态动词和虚拟语气。句意:结果是一个小的家庭聚会,我们本可不必穿得这么正式。B项中的need不是情态动词;needn’t have done本不必做某事(实际上却做了)。故选D。