Current changing in direction and rising and falling in value is ( ).

Pass me a ( ) , pleas

What is wrong ( ) you?

The designed ( ) is 20 tons per day, but the fresh water generator can only distil15 tons at present

( ) can be used to check the air leakage from the pip

( ) for fuel injection should be readjusted

Please choose a correct name for “泡沫灭火器”.

In a ( ) boiler the water flows through the inside of the tubes while the hotgases pass round the outside

If black smoke is coming from the exhaust stack of a diesel engine, what could be the trouble?( )

( )_ should be defroste

If you must enter a room to combat the fire, keep an escape path ( )