If separating effect is not good, which measure should be taken （）

Which of the diesel engine components listed increase air density and helps to improve engine operating efficiency?（）

For a given exhaust gas boiler, what is the quantity of its evaporation mainly determined?（）

If two A.C.generators are to be operated in parallel, the load is distributed evenly by（）

（）are used to digest the sewage to produce innocuous sludge in a biological sewage treatment plant.