Flame failure in an automatically fired auxiliary boiler can from a/an （）

Thermostatic steam pressure reducing valves are used in the fuel oil service system to control the（）

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

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

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

Engine parameters shall be corresponded to NOx Technical Files. This is required by （）

One of the reasons that cause oil flowed from sludge outlet of a self-cleaning separator is（）

Refrigerant entering the compressor of a refrigeration system should be in which of the following conditions?（）

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

Using a file without a handle may result in （）