981 、 Revisions are to be made consistent with the format of the specification using the provisions ofFAR21.50 as a basis. 修订应以 FAR21.50 的规定为基础，与规范的格式保持一致。

By using the basic provisions of FAR 21.50, revisions become consistent with the format of thespecification.

FAR21.50 provisions are the basic to the revisions which are consistent with the format of the specification.

To make reservations consistent with the format of the specifications, the provisions of FAR21.50 shouldbe adopted as a basis.

正确答案：B

507、Detection system is used to detect and indicate the formation of ice.

506、De-energize the system.it

505、Database synchronization is in progress.

504、Continuing Airworthiness Program Inspections usually consist of two pages one text page and lone illustration page.

503、Connect the towing arm to the nose gear.to

502、Connect the disconnected wires.

501 、Comments are located directly below the repair/modification section, extending from the left to the right margins.

500、Close valve A" when you get the same indications on gauges "X"AND"Y"."

499、CAUTION:WHEN YOU REMOVE THE PROBES,DO NOT LET THEM TOUCH EACH OTHER.

498、Carefully put the valve assembly in its position and install the spacers and the bolts.