停电时，首先迅速关闭离心泵的（），避免泵倒转。
A.入口阀门
B.出口阀门
C.回流管路阀门
D.放空阀门
参考答案：B
用于汽车减震器上的钢制弹簧片
With a lot of difficult problems ____ , the manager felt a heavy burden taken off his mind.
A．settled
B．to be settled
C．settling
D．to settle
