From quanta mechanical Angle looks, vacuum is not stable.
从量子力学的角度看，真空并不不乱。
Mechanical Propertise of Angle after Heat Treatment should in accordance with the following Table.
经热处理角钢的力学性能应符合下表规定。
Mechanical Propertise of Angle after Heat Treatment should in accordance with the following Table.
经热处理角钢的力学性能应符合下表规定。
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