单项选择题
A.rotary compressors B.reciprocating compressors C.centrifugal compressors D.screw compressors
Compressed air is used on board ship for all the follow...
单项选择题Compressed air is used on board ship for all the following purposes except （）.
A.starting diesel engines B.pneumatic control systems C.pneumatic tools D.supercharging air
Low pressure air is usually taken through （） or pressur...
单项选择题Low pressure air is usually taken through （） or pressure regulators to a low pressure reservoir supplying a ring main through driers.
A.globe valves B.butterfly valves C.gate valves D.reducing valves
A number of biological sewage treatment plants are in u...
单项选择题A number of biological sewage treatment plants are in use at sea but nearly all work on what is called the extended aeration processBasically the consists of oxygenating the liquor by bubbling air through itAccording to the above two sentences, the word "this" means （）.
A.a sewage treatment plant B.the extended aeration process C.the liquor D.the bubbling air
