问题
选择题
(2013·浙江金华二模)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
答案
答案：D
选D 句意：一项调查表明，在交通事故中丧生的人，如果当时一直系着安全带，那么他们中40%的人有可能不会丧命。根据“if they had been wearing”可知，此处是对过去情况的虚拟，主句谓语的形式应为“would/could/might/should＋have done”，排除B、C两项，根据句意应表示“可能”而不是“应该”，故选D。