液压系统B的EDP提供压力低于下面哪一个值时,向PTU控制活门的控制电路发送接地信号()
A、2750Psi
B、2350PSi
C、1600PSi
D、1300Psi
参考答案:B
We went through a period _____ communications were very difficult in the rural areas. [ ]
A. which
B. whose
C. in which
D. with which
凸轮与从动件有几种主要型式?各具有什么特点?