A towing light is（）. ["shown below the stern light","white in color","displayed at the masthead","a yellow light having the same characteristics as the stern light"]
Under normal conditions, the refrigerant enters the compressor in an operating refrigeration system as a （）. ["liquid","dry saturated gas","wet saturated gas","superheated vapor"]
阶式制冷深冷分离，最少需（）冷冻循环组成。 ["一个","两个","三个","两个以上"]
A towing light is（）. ["shown at the bow","white in color","shown in addition to the stern light","an all-round light"]
什么是美国西部片？
什么是CO2补偿点？
