单项选择题
The shutter of the evaporator was blocked with （）, it means there was too much evaporation.
A.ice B.wooden board C.iron plate D.cotton waste
单项选择题 The inner part of the condenser should be cleaned with （）.
单项选择题 In the cargo winch, spur reduction gearing transfers the motor drive to （）.
单项选择题 For occasional heavy loads, two cranes can be arranged to work together. The operating （） for deck crane motors may be hydraulic electric.
