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.
单项选择题 The main purpose of changing main engine to electronic controlled is not to（）
单项选择题 To meet the market requirements, a marine diesel engine should not be of（）
