_________ the car after drinking alcohol, there wouldn’t have been the accident.

A．Had he not driven

B．Hadn’t he driven

C．If he didn’t drive

D．If he doesn’t

软切换多条无关分支的存在降低了阴影衰落余量需求，由此带来的增益称为多小区（MultiCell）增益；而软切换对链路解调性能的增益称为宏分集（MacroDiversityCombining）增益。