单选题Proper lubrication of the main bearing is more easily obtained in a single acting four-stroke/cycle diesel engine than in a single acting two-stroke/cycle diesel engine because （）A bearing pressure in a four-stroke/cycle acting single diesel engine is

Radar is not only to obtain ______, but also to measure their distance away from you.

A.brightness of objects

B.color of targets

C.shape of targets

D.bearing of objects

The common method of applying oil to the cylinder walls is by means of small pump assembled in units, known as

A.mechanical lubricator

B.lubrication function

C.forced feed system

D.bearing lubrication

19．

A．easy

B．easily

C．easier

D．more easily

Adjust ______by means of lead wire.

A.the clearance of the main bearing

B.the diameter of main bearing

C.the gap of main bearing

D.the tolerance of main bearing

The most crucial time for any bearing with regards to lubrication is

A.during low loads

B.after proper oil viscosity is reached

C.during starting

D.after cleaning filters

Lubrication for the main reduction gears used with diesel engines is usually supplied by

A.oil from the main engine sump

B.an independent lube oil system

C.the stern bearing head tank

D.the stem bearing sump tank

Proper lubrication of the main bearings is more easily obtained in a single acting, four-stroke/cycle diesel engine than in a tow-stroke/cycle diesel engine because________.

A.The direction of pressure on the journal in four-stroke engine is continuously

B.positive feed lubricators are installed on all bearings of four-stroke engine, whereas as a splash feed system is used on tow-stroke engine

C.four-stroke engines usually utilize a heavier grade of oil than tow-stroke engines

D.Low-stroke engines usually consume less lube oil than four-stroke engines