下水井井盖、电缆沟盖板开启后应设置()围起,并有人看守。工作人员撤离电缆井或隧道后,应()将井盖盖好。 ["标准路栏","标志物","立即"]
JZ-7型制动机单阀中调整阀是把列车管压力空气供给作用阀使机车制动。
关于曲柄摇杆机构,说法正确的是() ["只能将曲柄的主动转动转变为摇杆的摆动","只有一个连架杆为曲柄","只可以以曲柄为主动件","机架为最短杆"]
柴油机长时间连续运转,负载不得超过标定功率的90%。()
Cottonseed oil is classed as a(). ["combustible liquid","flammable liquid","flammable solid","poison B"]
双极分化