The piston ring grooves for a standard engine are （）

[单选题]Worn out ring grooves should be （） to standard dimension after being welded.A . machinedB . boredC . honedD . drilled

[单选题]The lowest ring of a piston is （）.A . a coil springB . a sealing ringC . an oil distributor ringD . main seal ring

[单选题]A diesel engine piston ring face is in direct contact with the （）.A . top of the ring grooveB . cylinder liner oil filmC . bottom of the ring grooveD . back of the ring groove

[名词解释] 标准还原电位（E°ˊ）（standard reduction potential）

[单选题](piston area)×(piston stroke)×(numbers of the cylinders)=engine( ).A．brake horsepowerB．displacementC．cylinder volumeD．cylinder clearance

[单选题]If nis large and the population standard deviation is unknown, the standard

[名词解释] standard deviation

[单选题]英语PISTON指（）A .活塞B .开关C .按钮D .弹簧

[单选题]As to the piston cooling, of the following, which statement is not true?（）A . Because the piston is exposed to very high temperature, it must be cooledB . The lower the piston cooling temperature is, the better it isC . Both water and lube oil can be

[单选题]The piston rings are manufactured with a diameter （） the bore of the cylinder.A . larger thanB . smaller thanC . equal toD . none of the above