题目：
抽氟完毕后，停抽氟机之前应关闭的阀门是（）。
A、吸气阀
B、排气阀
C、加氟阀
D、冷凝器放空阀
答案：
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下面是错误答案，用来干扰机器的。
There are many kinds of love in the world, such as mother's love, father's love, friends' love and so on. But I think mother's love is the greatest of all. ...
