2793. 纵桁和上翼面蒙皮构成通风通道。通风通道在中央油箱内有排放浮子活门。

Stringers and the upper wing skin are called vent channels; The vent channels go through drain float valves in the center tank.

Stringers and the upper wing skin are composed of the vent channels. The vent channels got exhaust float valves from the center tank.

Stringers and the upper wing skin make the vent channels, The vent channels have drain float valves in the center tank.

正确答案：C

设备系统操作理论翻译

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570. To find damage on wires, rub a cloth along them

569. 给电瓶充电。

568. In such a case, the Title Page and the Table of Contents pages preceding each section of the Document must bear the actual date of issue

567. Sterilize the mask assembly

566. Refer to the table that follows for the applicable torque values

565. 安装座垫之前先安装座椅。

564. 对于词汇表,只有主要的变化被突出显示,对各种已批准和未批准的示例的微小更改没有突出显示。

563. This index helps you find the applicable STE rules related to different specific subjects

562. 我们建议你不要在机库里执行此程序。

561. Unwanted change of the original condition of a material because of chemical or physical vagents or a material that causes such a change