在3Dmax中，单视图最大、最小化的快捷键是（）。
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空气压缩机基本分为三种，即活塞式、螺杆式、隔膜式。
A. 正确
B. 错误
The procedures recommended for auxiliary boilers having high salinity include （）.
A. treating with oxygen scavengers
B. securing the boiler and giving it a blowing down
C. increasing the pH
D. reducing the phosphate level
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