【题目】It was so noisy outside that we ____________ hear what they were talking about.
A. mustn't B. didn't have to
C. ought not to D. couldn't
在线课程【答案】D
【解析】考查情态动词。A. mustn't禁止，不允许；B. didn't have to不必；C. ought not to不应该； D. couldn't不可能。句意：外面如此吵闹，我们不可能听到他们在谈论什么。故选D。