When the amount of lubricating oil injected into the bearing box of the centrifugal pump is too much, it will not cause ( ).

Lube oil "five definite" is designated person, ( ), time, quality and quantity.

Temporary power lines with a service cycle of more than 1 month should be installed by overhead and meet the requirements of ( ).

If the workplace is wet, to avoid electric shock, people using hand-held power tools should ( ).

Under international regulations, voltages below ( ) do not have to be considered to prevent the danger of direct shock.

The dangerous voltage for an electric shock generally starts at ( ) volts.

Do not use ( ) to extinguish fires when electrical appliances are on fire.

A fire extinguisher that should not be used in the event of a fire in electrical equipment is ( ).

The following not suitable for putting out electrical fires are ( ).

Foam extinguishers are mainly used to put out ( ) initial fires.

When the wind is off, operate the self-controlled air opening control valve ( ).

The following units should use the air shutoff valve is ( ).

Whether the control valve uses a gas open valve or a gas close valve is considered from the point of view of ( ).

The following statement about the selected principle of control valve air on and off is correct ( ).

High temperature media piping is generally used on ( ).