One of the most common causes of reduction gear failure is gear wear caused by scoring as a result of

A．surface fatigue of the gears

B．an inadequate lube oil film

C．plastic flow of the gears

D．fretting corrosion from water

[单选题]______ the most versatile of the common metals, lead was widely valued and used in ancient times.A． It isB． ThereforeC． AmongD． Because

[单选题]One of the reasons that causes oil flowed from sludge outlet of a self-cleaning purifier isA．seal water supply be cut offB．make-up water supply be cut offC．oil outlet valve closed or not open sufficientlyD．the flow rate of oil is too much

[单选题]The most important factor that causes the wear of the engine parts is （）.A . excessive heatB . frictionC . oxidationD . high pressure

[单选题]The most common contaminate of governor hydraulic fluid is （）.A . moistureB . dirtC . acidD . air

[单选题]The display screen is the most common (72) device used to show you what the computer is doing．A．inputB．printingC．outputD．electronic

[单选题]The most common query language is______．A．CB．JavaC．perlD．SQL

[单选题]The most common method of securing a line to a cleat is a（）.A . half hitch，then round turnsB . round turn，then figure eightsC . figure eight，then round turnsD . figure eight，then half hitche

[单选题]The most common type of containment device for spilled oil on the water is the use of _____.A．strawB．boomsC．skimmersD．chemical dispersants

[单选题]In practice， a set of（ ）originalbills of lading is the most common.A.oneB.t

[单选题]In practice， a set of（ ）originalbills of lading is the most common.A.oneB.t