单选题 Ship propulsion normally occurs with the help of a ______, which is the term most widely used in English, although the word "screw" is sometimes seen, inter alia in combinations such as a "twin-screw" propulsion plant. 船舶推进通常借助 ______，这是英语中最广泛使用的术语，但有时也会出现 “螺杆 ”一词，特别是在 “双螺杆 ”推进装置等组合中。

单选题 The low speed diesel engines are tall to allow for long strokes which improve engine ______. 低速柴油发动机高，冲程长，提高了发动机的______。

单选题 The influence of frictional and residual resistances depends on how much of the hull is ______ the waterline, while the influence of air resistance depends on how much of the ship is ______ the waterline.3、摩擦阻力和残余阻力的影响取决于船体 ______ 水线的多少，而空气阻力的影响取决于船体 ______ 水线的多少。

单选题 Medium speed engines are used widely as ______ engines in most merchant cargo ships. 中速发动机作为 ______ 发动机广泛应用于大多数商船货轮。

单选题 Most ships that do not need a particularly good manoeuvrability, such as ocean-going container ships, tankers and bulk carriers are equipped with a ______, as it offers the highest efficiency.

远洋集装箱船、油轮和散货船等不需要特别好的机动性能的船舶大多配备 ______，因为它的效率最高。

单选题 The main operating characteristic of diesel engines which distinguishes them from other internal combustion engines is the ______. 柴油机区别于其他内燃机的主要工作特性是 ______。

单选题 The ______ engine is used for alternators and sometimes for main propulsion with a gearbox to provide a propeller speed of between 90 to 120 r/min. ______ 发动机用于交流发电机，有时也用于主推进，配有变速箱，可提供 90 至 120 r/min 的螺旋桨转速。

单选题 Large, slow speed, two-stroke marine diesel engines are directly coupled to propeller and do not require a ______. 大型、低速、二冲程船用柴油机直接与螺旋桨连接，不需要 ______。