A survey has shown that 40% of those killed in traffic accidents if they had been wearing seat belts.
A. should have been saved
B. must have been saved
C. need have been saved
D. could have been saved
网友回答
A. should have been saved
B. must have been saved
C. need have been saved
(答案→)D. could have been saved
解析：考查情态动词+完成式的用法：句意：一项调查表明40%的在交通事故中丧生的人如果戴好安全带可能就能得救。用could have done表示“本来可能做却没有”，Should have done本应该做而没有，must have done一定做过…，need have done本需要做却没有做，都不符合句意，选D。