All the rings are slightly rounded on their external top and bottom edges to keep the oil film on the cylinder liner during （） for new piston rings.

[单选题]The film of oil between the rings and the liner is not only essential for the lubrication but also plays an important part in achieving （）.A . an oil sealB . removing heatC . a gas sealD . cooling the pisto

[试题]A．llthestudentsinthisclasspassedtheEnglishexam________theexceptionofLiMing.A．)onB)inC．)forD)with

[单选题]The passengers were robbed ______ all their money.A． ofB． offC． fromD． away

[单选题]The phrase “make serious cash off all the consumers” (Paragraph 2) means “_________ ”A． make consumers deposit all their money into bankB． cause the consumers to use up all their moneyC． make all the consumers cash their money' in the bankD． make a

[单选题]（）crowded orders；we have sold out all the goods scheduled for shipment with in this year.A . Asa result ofB . In result ofC . With there sult ofD . As result of

[单选题]For two bonds that are alike in all respects except maturity, the relative

[单选题]The ship should have a slightly deeper draft（）.A . on port sideB . on starboard sideC . at the port quarterD . at the ster

[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

[单选题]The sealing rings are in four parts and pressed together around the piston rods by means of _____A．nutsB．boltsC．coil springsD．stuffing boxes

[单选题]The sealing rings are in four parts and pressed together around the piston rods by means of （）.A . nutsB . boltsC . coil springsD . stuffing boxe