1.Valve leakage is generally categorized as through the valve, outside the valve, and outside-to-______ the valve.
1.阀门泄漏通常分为三种类型：穿过阀门泄漏、阀门外部泄漏，以及从外部向______阀门内部泄漏。
2.Heavy-duty Type I grease ducts are constructed from which steel?
2.重型 I 类排油烟管道（grease ducts）应采用哪种规格的钢材制作？
3.Which hand signal directs a crane operator to STOP?
3.哪种手势信号是指示起重机操作员“停止”（STOP）？
4.If a condenser fan is off balance, the most likely cause is:
4.如果冷凝器风扇失去平衡，最可能的原因是：
5.If a compressor oil charge is unbalanced, the likely cause is:
5.如果压缩机的充油量失衡，可能的原因是：
6.Before recharging the system after replacing a condenser or compressor, the refrigerant system should be:
6.在更换冷凝器或压缩机后，重新向系统充注制冷剂之前，应先对制冷系统进行：
7.Freeze-up of capillary tubes or expansion valves is caused by:
7.毛细管或膨胀阀发生结冰堵塞，通常是由什么原因引起的？
8.During rigging, if an electrical pole obstructs the path, the correct action is:
8.在进行起重吊装作业时，如果电线杆阻碍了作业路径，正确的处理方式是：
9.Another blended refrigerant that can replace R-12 is ______.
9.另一种可以替代 R-12 制冷剂的混合制冷剂是 ______。
10.Which material has the lowest insulation value (R-value)?
10.下列哪种材料的绝缘性能值（R值）最低？
