“上边毛，下边毛，中间有颗黑葡萄”，如右图能调节瞳孔大小的是（） 1。 2。 3。 4。
简述冲击式汽轮机级的工作原理和级内能量转换过程及特点。
Cast iron pistons used in large propulsion diesel engines are constructed with （） not taper what so ever。 the skirt being tapered and smaller than the crown。 the skirt being tapered and larger than the crown。 the crown being tapered and smaller than the skirt。
The daily predictions of the times and heights of high and low water for a selection of Standard Ports are given in（）. Admiralty Maritime Communications。 Admiralty Tide Tables。 a comprehensive guide for the yachtsman。 ALRS。
什么许多航运企业优先建立质量安全管理体系、实施双标认证？
丙纶丝滤机反洗时要保证压缩空气间断连续运行，避免发生压缩空气管路进酸性水而（）管路。
