空调机冷凝器太脏，制冷系统中将出现（）和压缩机超载。
水泥砂浆用于桥涵附属建筑物，防护铺砌、拱桥填腹等，不低于（）号。
A. M5
B. M7.5
C. M10
D. M15
The principal purpose of sub-cooling liquid refrigerant prior to its entering the expansion valve is to （）.
A. increase the refrigerating effect, by decreasing the amount of flash gas
B. allow the refrigerant to enter the throttling device in a saturated condition
C. increase the refrigerating effect by increasing the amount of flash gas
D. minimize the temperature drop of the liquid as it passes through the solenoid valve to the outlet side
在教育中搞“一刀切”、“一锅蒸”，强凋儿童“成人化”，违背了教育的（）规律
A. 人不平衡性
B. 个别差异性
C. 顺序性
D. 阶段性
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