The maximum permitted difference is 5 mm.

A. Clean all lint, dust and debris from the ventilation holes located on the aft side of the captain＇s primary flight, navigation, and center lower engine display units.

B. Clean the vent holes behind the captain＇s primary flight, navigation and lower middle engine display units which are blocked by lint, dust and debris.

C. The captain＇s primary flight, navigation, and center lower engine display units must be cleaned since the ventilation holes behind them are clogged by lint, dust and debris.

A. 对于利用空气作为防冰介质的涡轮类动力装置，发动机防冰功能包含在空气系统中。

B. 因为涡轮类型动力组合使用气体作为防止积冰的渠道，发动机防积冰设备被储存在空气系统下。

C. 因为涡轮动力装置将空气用来防止积冰，发动机防冰包含在通风系统中。

A. Explaining how to obtain the maximum ground miles per gallon through careful flight planning and attention to good operating procedures is the primary content.

B. Display how to achieve the main objective to get the greater ground miles per gallon by careful flight planning and attention to good operating procedures.

C. The principal purpose is to show how to increases the ground miles per gallon as much as possible with careful flight planning and attention to good operating procedures.

A. 描述飞机发动机时，应简要阐述异常运行。应保持在最低限度以帮助飞行员纠正形势或使他能够向机械师描述情况。它不应是一个维修程序。

B. 描述飞机发动机时，应简要阐述非正常运行。应在最低限度帮助飞行员改正情况或使他能够向机械师描述情况。它不应是一个维修程序。

C. 描述飞机发动机时，应对非正常运行情况进行简要描述。应以帮助飞行员纠正非正常情况或使其能够向机械师描述非正常情况为宜。无须是具体的维修程序。

A. 当需要了解膜片时，使用箭头指示方向。

B. 必要时应使用箭头表示流向来理解原理图。

C. 利用箭头指示的方向来理解线路施工图。

A. Record the results if the frequency changes.

B. Alter the phase and record the results.

C. Change the frequency and record the results.

A. 为了简化阅读和相互援引，插图、图形和表格应尽可能以纵向排列布局呈现。

B. 为方便阅读和相互参照，如可行，插图、图形和表格应垂直排列布局。

C. 为了精简阅读和交叉索引，插图、图标和表格如可行，应纵向排列布局。

A. The accuracy of the adjustment can vary.

B. The accuracy of the adjustment can be fixed.

C. The precision of the adjustment can be prevented .

A. Do a thorough check of the hydraulic system.

B. Do a check of the hydraulic system carefully.

C. Do a check of the hydraulic system again.

A. The fuselage includes skin, stringers, frames, floor beams, floor, tail cone, and fuselage to wing and tail fittings, etc.

B. The fuselage includes skin, frames, stringers, floor beams, floor, tail cone, and fuselage to wing and empennage fillets, etc.

C. The fuselage includes skin, beams, stringers, floor frames, floor, tail skid, and fuselage to wing and rear fairings, etc.