If you have to jump in the water when abandoning a vessel,your legs should be().
A. spread apart as far as possible
B. held as tightly against your chest as possible
C. in a kneeling position
D. extended straight down and crossed at the ankle
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试分析用平旋盘刀架镗孔及用主轴镗孔时,同轴度超差的原因。
危险化学品出入库,必须进行核查登记,库存危险化学品应定期检查。
A. 正确
B. 错误
磁子午线和真子午线之间的夹角叫()。以真子午线为准,磁子午线东偏为正,西偏为()。