1.R-134a is an HFC refrigerant designed as a long-term replacement with properties similar to ______.
1.R-134a 是一种 HFC 类制冷剂，被设计作为一种长期替代品使用，其理化特性与 ______ 相似。
2.If soot is observed on a burner flame, what adjustment should be made?
2.如果在燃烧器的火焰中观察到烟灰，应进行何种调整？
3.Flue gas refers to which of the following?
3.烟气（Flue gas）是指下列哪项？
4.When replacing a compressor, the safest way to remove the refrigerant lines is to:
4.更换压缩机时，拆卸制冷剂管路最安全的方法是：
5.Before performing tests on a TXV system, make sure the ___is properly secured and that the suction line is insulated.
5.在对TXV（热力膨胀阀）系统进行测试之前，请确保___已妥善固定，且吸气管已进行绝热处理。
6.When performing a leak test using nitrogen or nitrogen/helium mix, the system must hold a pressure of___for at least 10 minutes.
6.当使用氮气或氮气/氦气混合气体进行检漏测试时，系统必须保持___的压力至少10分钟。
7.Which refrigerant was eliminated from production in 1996?
7.哪种制冷剂于1996年停止生产？
8.The most precise method for checking refrigerant charge is by measuring___with manifold gauges.
8.检查制冷剂充注量最精确的方法是使用复式压力表组测量___。
9.The Minimum Efficiency Reporting Value (MERV) is used to:
9.“最低效率报告值”（MERV）用于：
10.Air conditioning systems should not be operated or tested outdoors when the temperature falls below___.
10.当室外温度降至___以下时，不应在室外运行或测试空调系统。
