燃气计量表必须经过（）检定机构的检定，检定日期应在有效期限内。 ["工程计量","法定计量","分析仪","检测仪"]
Which of the valves listed should be used either in the fully opened or the fully closed position?（） ["A gate valve","A globe valve","Any check valve","Any needle valve"]
下列说法中，不属于前置液作用的是（） ["破裂地层","造成一定几何尺寸的裂缝","冷却地层","将携砂液顶替到预定位置"]
压裂液是一个总称，根据其在施工过程中任务不同，可分为（）、携砂液和顶替液。 ["泡沫液","前置液","乳化液","水基液"]
If a refrigeration compressor is running continuously without lowering the temperature in the refrigerated space, the trouble may be （）. ["a shortage of compressor oil","warm food in the refrigerator","excessive condenser cooling water","a shortage of refrigerant"]
植物的光呼吸和暗呼吸的有哪些区别？
