In order to prevent failure of packer and provide theoretical basis for selection of unsetting shear pin, the unsetting force of packer must he calculated in design.
As the unsetting polar star, which through the livelong, arctic, six months' night sustains its piercing, steady, central gaze; so Ahab's purpose now fixedly gleamed down upon the constant midnight of the gloomy crew.
作过程中失效，并为解封
钉（或
，必须进行解封力的设计计算。
，经过长达六个月
持着它锐利、稳定、集中
也是如此，死死地照在永远如午夜般阴郁
