Use disinfectant to clean the mask assemblies.

A. 直升机最常用的两类发动机是星型发动机和涡轮发动机。

B. 螺旋桨飞机最常用的两类发动机是往复式发动机和涡喷发动机。

C. 直升机最常用的两类发动机是活塞发动机和涡轮发动机。

A. All of the top vertical mounting struts are adjustable except the primary mount struts unless they are repaired or replaced. The spare vertical strut (left forward ) and the side strut (right forward) may require adjustment during APU replacement.

B. All of the vertical primary mount struts at the top are adjustable. However, adjustments to the primary mount struts are not required unless a strut is repaired or replaced. The redundant vertical strut (forward left) and the redundant side strut (forward

C. The top of every vertical main retaining struts is adjustable. However, adjusting the main mount strut is not allowed if the strut is not repaired or replaced. During APU replacement, it may be necessary to adjust remained vertical strut (left anterior) a

A. Put the actuators against the tires.

B. Put the chocks against the wheels.

C. Put the chain against the brakes.

A. When you lift the aircraft on racks, keep the center of the aircraft between these limits.

B. When you lift the aircraft on jacks, keep the center of gravity between these limits.

C. When you lift the aircraft on jacks, the gravity of the aircraft shall be limited.

A. The radius of the duct is too small.

B. The diameter of the tube is too small.

C. The circumference of the pipe is too small.

A. However, an “emergency” almost always entails a failure that requires to respond immediately and rapidly, for example, the situations that a total powerplant fails, the fire or smoke occurs, or the cabin are depressurized rapidly.

B. An “emergency” however, almost always causes a malfunction that requests immediate and rapid response, such as the whole powerplant failure, fire or smoke, or rapid cabin pressurization.

C. However, an “emergency” is often related to a failure that demands respond simultaneously, such as the complete failure of the powerplant, fire or smoke, or rapid cabin warming.

A. The unit of all range distances shall be nautical mile.

B. We measure all range distances in accurate miles.

C. The range of distances shall be calculated in knots.

A. 附件的信息可能会通过定期培训要求传达给所有员工。

B. 额外的信息可以通过定期培训要求传达给所有员工。

C. 增加的信息可以通过复训要求传达给现有员工。

A. STE was researched to help the writers of English-language file understand what they write, particularly when these writers are non-native English speakers.

B. STE is prepared to make readers of English-language documents know what they read difficultly, especially when these readers are native English speakers.

C. STE was developed to help the readers of English-language documentation understand what they read, particularly when these readers are non-native English speakers.

A. 描述飞机螺旋桨时，如果合适，应阐述正桨、反桨和反转。

B. 描述飞机螺旋桨时，如适用，应描述顺桨、解除顺桨和反桨相关信息。

C. 描述飞机螺旋桨时，如果合适，应讨论顺桨、不反桨和反推。