A.bottom-blow valveB.skin valveC.feed-check valveD.feed……

单项选择题The mechanical exhaust valve operation system is replaced by（）in an electronic controlled ME engine.

A.a system with a Hydraulic Power Supply (HPS) unit
B.a system with roller guides for exhaust valves
C.a system with an electronically controlled Alpha Lubricator
D.a system directly powered by electric motor

单项选择题（）is not a feature of the electronic controlled engines.

A.Lower fuel consumption
B.Better balanced cylinder power
C.A shorter overhaul period
D.Less smoke emission

单项选择题If a camshaft-less engine has a normal injection pressure at rated speed, the injection pressure will be at slow speed（）

A.too low
B.a little lower
C.a little higher
D.exactly the same

单项选择题If a cam-controlled engine has a normal injection pressure at rated speed,the injection pressure will be（）at slow speed.

A.a little lower
B.a little higher
C.too low
D.exactly the same

单项选择题The main purpose of changing main engine to electronic controlled is not to（）

A.control fuel injection time more precisely
B.control fuel injection rate more precisely
C.meet the environmental requirements
D.meet high engine speed requirements