—I really don't know what I yesterday without the bike you lent me.—Glad to have been some

网友回答

A. could do
B. should have done
C. had done
(答案→)D. could have done
解析：考查虚拟语气。因为本句是对昨天的情况进行说明，故使用情态动词+have done的形式，could have done本可以做某事；should have done本应该做某事，实际上却未做；句意：—我真的不知道没有你借我的自行车，我昨天可以做什么。—很高兴能帮到你。故D正确。