Correct punctuation is important because it shows how the different parts of the text are related and prevents ambiguity.

A. The rudder can be used in case of thrust asymmetry.

B. The vertical stabilizer can be used in case of throttle symmetry.

C. The rudder can be used in situations where thrust is symmetric.

A. 门是由基础复合材料增强塑料制成的。

B. 门是由碳纤维复合塑料制成的。

C. 门是由碳纤维增强塑料制成的。

A. Ensure that there is no corrosion on the tubes.

B. Make sure that the tubes have no deformation.

C. Make sure that the tubes have no crack.

A. 建议在飞行50小时内不要拧紧螺栓。

B. 建议在飞行50小时前重新拧紧螺栓。

C. 建议在飞行50小时后再次拧紧螺栓。

A. Substitutes with different quality can be used.

B. You can not use substitutes with same quantity.

C. Equivalent substitutes are permitted to use.

A. 从地板护盖上去除剩余的密封胶。

B. 保留地板护盖上残存的溶剂。

C. 去除地板护盖上剩余的溶剂。

A. 确保L和R PACK开关在P5-10空调面板上显示OFF位。

B. 确保P5-10空调面板上的L和R PACK开关处于OFF位置。

C. 确保P5-10面板上的L和R PACK在OFF位时，空调按钮在关闭位。

A. 液压系统包括将一定压力（包括泵、压力调节器、管路、阀门）的液压油输送到一个汇聚点（总管），再分配到用户系统的部件和组件。

B. 这些单位和组件在压力作用下将液压油输入到包括油泵、压力调节器，管路，活门等部位，最后到达一个公共地点，即分配阀，是为了再次分配到其他设定好的系统中。

C. 这些单位和组件将液压油输入到各个压力组件中，包括油泵、压力调节器，管路，活门等。后来液压油汇聚到一个通用点（分配阀），为了再分配到其他定义好的系统中。

A. However, manufacturers are following the same fundamental systems and sequence of subject arrangements even if some systems, which are not available, may be bypassed.

B. Nevertheless, each manufacturer is expected to follow the same sequence of basic system and subject arrangements even though some systems may be omitted when not applicable.

C. Even so, all manufacturers are expected to submit to the same arrangements of main systems and subject sequences even though certain systems would be ignored when not applicable.

A. The total quantity of fuel in the center tank is 5000 lb.

B. The Total Fuel Quantity of the main tank is 5000 pounds.

C. The total fuel consumption from the center tank is 5000 pounds.