12. Most American cities are relatively small _____ population when compared with Shanghai and Beijing.

A．as well as

B．by means of

C．except for

D．in terms of

MGB1420万能磨床控制电路电气故障检修时，自动循环磨削加工时不能自动停机，可能是电磁阀YF线圈烧坏，应更换线圈。