如图所示电路，两盏相同的电灯在闭合开关后都能发光。过了一会儿，两盏电灯突然同时都不亮了，且电压表和电流表的示数均变为零。如果电路只有一处故障，则故障可能是（    ）

A．电灯L₁短路

B．电灯L₁开路

C．电灯L₂短路

D．电灯L₂开路

Old McDonald gave up smoking for a while, but soon _____ to his old way.

A．returned 　

B．returns

C．was returning

D．had returned