The efficiency of coal－charging machine is very high, ______, 1 500 tons of coal per hour.

The size of the discharge ring used for the efficient operation of a disk type purifier is dependent upon the ___.

I was impressed _______ the efficiency of the work

Japanese firms have achieved the highest levels of manufacturing efficiency in the world a

What is the recommended stock of coal？A．B．C．

Charging is the filling of the engine cylinder with a supply or charge of fresh air _____

Which of the following is NOT a reason for the low efficiency of the labor market at match