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.
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（）
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.