单位长度扭转角
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
一圆轴用碳钢制作,校核其扭转角时,发现单位长度扭转角超过了许用值。为保证此轴的扭转刚度,采用哪种措施最有效________。
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