单项选择题
（）uses one or two high pressure pumps for all the cylinders with one more standby, while（）have a separate high-pressure pump for each cylinder.
A.A common rail engine；conventional engines B.A conventional engine；common rail engines C.A marine diesel engine；most other engines D.A two-stroke engine；four-stroke engines
单项选择题 In a common rail engine, the fuel is injected into cylinders（）
单项选择题 In common rail engines, the fuel is（） before is injected into the cylinders.
单项选择题 In conventional systems, the injection pressure（）, while it’s（）in common rail diesel engines.
