___a few minutes earlier,the pollicemen would have caught the murderer.A.If they arrivedB Had they arrived为什么不选A?选B

问题描述:

___a few minutes earlier,the pollicemen would have caught the murderer.
A.If they arrived
B Had they arrived
为什么不选A?选B

、、、、、

这是if 引导的虚拟从句 是对过去的虚拟 从句省略if 用了倒装 完整的语句是if they had arrived a few minutes earlier