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问题 单项选择题

外平衡式热膨胀阀的平衡管结霜表明（）。

A．蒸发温度太低

B．蒸发器制冷剂出口过热度太低

C．膨胀阀制冷剂流量太大

D．膨胀阀波纹管顶杆填料漏泄

答案

参考答案：D

选择题

_______the people have become masters of their country _______ science can really serve the people.

A．It is only then; that

B．It was that; when

C．It is only when; that

D．It was when; then
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单项选择题

烟叶从成熟一完熟一过熟，其油分呈（）趋势。

A．下降

B．增加

C．上升

D．不变
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