问题补充：
The safety belt saved the boy; otherwise, he in the accident.
A. would be killed
B. was killed
C. had been killed
D. would have been killed
答案：
A. would be killed
B. was killed
C. had been killed
(答案→)D. would have been killed
解析：试题分析：句义：安全带救了那个男孩，否则他会在事故中死亡。Otherwise相当于一个对过去虚拟的条件句：if he handn’t tied the safefy belt.对过去的虚拟主句用would have done 所以D正确。
