A pump is said to have "negative suction head" when the pump is located ().
A. between the suction and discharge
B. below the liquid supply
C. above the liquid supply
D. any of the above
在备用刹车带防滞方式中,BSCU控制什么来实现防滞规则()
A. 备用伺服活门;
B. 压力控制活门;
C. 双活门
Inmarsat-F系统规定的通信等级中,安全通信等级代码是()。
A. 0
B. 1
C. 2
D. 3