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单选题
Those units and components (ducts and valves) deliver large volumes of compressed air from a power source to connecting points for such other systems as environmental controls, deicing, etc.
A
Those units and components, including ducts and valves, transfer large volumes of compressed air from a power source to points of junctions for other systems , such as environmental controls, deicing, etc.
B
Those units and components (referring to ducts and valves) use a power source to compress large volumes of air, and then send air to other systems as environmental controls, deicing, etc.so they can build connections.
C
A great deal of compressed air is moved by those units and components (ducts and valves) , from a power source to connecting surfaces and other systems including environmental controls, deicing, etc.
答案解析
正确答案：A
