By using the role and the drafting methods, projective contour line of a quadric at random position can be drawn.

利用这一规律和作图方法，可以解决任意位置的非退变二阶曲面的投影轮廓线的作图问题。

youdao

Methods: Divide all HPH cases into two groups at random, 28 cases in Feiyanping group and 19 cases inNifedipine group as contrast.

方法：低氧性肺动脉高压症患者随机分为两组，28例用肺压平复方治疗，19例用硝苯地平治疗，两组进行观察对比。

youdao

Methods In each province, 3 counties were selected at random in each prefecture, 1~3 villages were selected at random, total 30 village were selected.

方法各省在每个地级行政区划单位随机抽取3个县，每个县随机抽取1～3个行政村，全省总数不少于30个。

youdao

Steffen considered various methods, such as boarding people in blocks, at random, and in window seats first.

FORBES: Sometimes Science is Behind the Curve