842、Adjust the potentiometer until you do not hear a hum from the loudspeaker. 调整电位器，直到你听不到从扬声器发出的嗡嗡声。

646、The first step should always be job Set-up and last should be Close Up or Clear-Up.

645、The elevators must move symmetrically.

644、The control units is installed aft of the cockpit.

643、The color of the indicator changes to green.

642、The Check list may also contain supplemental information pertinent to the operation of the airplane.

641、The center of gravity(is the point an airplane would balance if suspended.

640、The CAP will address primary and secondary airframe components. and primary and secondary systems to accomplishthe stated objective of continued airworthiness

639、The CAP is not intended to change or replace any portion of the applicable airplane maintenance manual

638、The battery energizes the emergency exit light circuit.

637、The approved repair portion shall include processes and techniques necessary for performing a repair.