In the refrigeration system, a shortage of refrigerant is indicated by （）. ["the compressor short cycling on high pressure cut out switch","high suction pressure","high head pressure","bubbles in the sight gla"]
铜管宜采用牌号为（）的管材。
什么是压力流学说？
Which of the following conditions must exist for heat to flow from one object to another?（） ["The two objects must be in physical contact","The two objects must be the same size","There must be an existing temperature differential","There must be an existing weight differential"]
新模式的核心风险理念是“收益覆盖风险加成本”与（）。 ["A.综合收益最大化","B.尽职者免责、失职者问责","C.杜绝风险","D.积极把控合规风险"]
什么是聚会礼仪？
