人民警察在交通管理及街面巡逻时，在执勤姿态方面有哪些基本要求？
If a heavy sea strikes the rudder, the shock is transmitted through （） to the rams, this cause a sudden increase in oil pressure in one of the cylinders. the control rod。 the hunting gear。 the floating ring。 the tiller arm。
压力机有哪些保护措施？作用是什么？
简述沙市刺棘头病的治疗方式。
The difference in water spray pattern between the high-velocity tip and low-velocity applicator used with the all-purpose nozzle is due to（）. a difference in water pressure。 the method of breaking up the water stream。 the length of the applicator。 All of the above。
The direction a vessel is pointed at any given time is the（）.
