Turbine engine tachometers usually measure speed as a percentage of the nominal maximum speed of the turbines.

A. The aircraft navigation systems provide the flight which is required by the crew,and meet the the most provisionally safety requirements.

B. The aircraft navigation systems provide the flight which is required by the crew,and meet the the most appropriate safety requirements.

C. The aircraft navigation systems provide the crew with the data required for flight within the most appropriate safety requirements.

A. The rules containing in this specification shall provide a guide to the formatting, type and method of all present documents in the manufacturer＇s maintenance manual.

B. The rules in this specification are served as a guide for the format, style and way of representation for all materials contained in manufacturer＇s maintenance manual.

C. The rules contained in this specification shall serve as guides for format, style and method of presentation for all material included in maintenance manuals prepared by manufacturers.

A. Open the isolating valves.

B. Open the check valves.

C. Open the bypass valves.

A. 不要使钢索散开。

B. 不要使电缆扭结。

C. 不要使导线绞缠。

A. Before restarting the engine, make sure to clear the ground from any fuel spills.

B. Remove all spilled fuel from the ground before making the first attempt to start the engine.

C. Ensure that no fuel on the ground is eliminated before proceeding with engine startup.

A. To make sure that ATC transceivers are in standby mode, you must simulate altitude, otherwise false TCAS signals may occur intermittently.

B. Make sure the ATC transmitters are in standby mode, or false TCAS targets may occur accidentally due to altitude simulation.

C. Make sure that the ATC transponders are in standby mode when you simulate altitude. You can accidentally cause false TCAS targets.

A. 涡轮发动机包括用于控制通过发动机空气流量的压缩机排气系统，用于发动机除冰的冷却空气系统，以及发动机启动系统。

B. 涡轮发动机包括压气机引气系统、空气冷却系统、热空气系统、发动机启动系统，其中压气机引气系统能控制通过发动机的空气流量，空气冷却系统和热空气系统用于发动机防冰。

C. 涡轮发动机包括控制通过发动机空气流量的压气机引气系统、空气冷却系统、用于发动机防冰的热空气系统和发动机启动系统。

A. Roger that, clear for dispatch.

B. Copy that, clear for pressing.

C. Roger, clear for pushback.

A. Thus, the more words there are in a cluster, the more difficult it is to understand.

B. Therefore, the more words are there in a phrase, the more difficult it is to understand.

C. So, the more nouns in a phrase, the harder it is to understand.

A. 在外表面上涂抹密封胶。

B. 在外壁板施加载荷。

C. 在外壳上喷涂防锈剂。