He kept his head otherwise the accident would have happen为什么用would have happen 而不用过去时happened或用would happen呢不好意思 happen 应改为happened
问题描述：
He kept his head otherwise the accident would have happen
为什么用would have happen 而不用过去时happened或用would happen呢
不好意思 happen 应改为happened
答
因为这个事故还没有发生，使用过去将来时。来表现通过kept his head 这个动作才能使事故不发生。
答
他保持头脑清醒 否则就会发生事故
答
是would have happened.情态动词过去时 + 完成时表示对过去事情的推测.这里也是一样..表示推测"要不是他kept his head,就会发生一场事故"...例如:I would have done my homework if I wasn't ill.如果不是我病了,我...
答
原句绝对有错。
应用WOULD HAVE HAPPENED
另外我觉得前面也有错，KEPT HIS HEAD后面应该还有个副词。
回答完毕。
P。S。过去将来时是这么用的吗？！楼上不要乱讲。再说这也不是过去将来时。是虚拟语气，虚拟过去。