but for his timely arrival,the boy _drowned.

题目

but for his timely arrival,the boy _drowned.
A would be B would have been
为什么选B而不选A呢?

答案

这是一个虚拟语句固应该率would0be但考虑到时态（很显然是对现在造成了影响）故用完成时的虚拟语句所以选择B