问题：
[单选] Each cylinder has one starting valve which is usually opened by air pressure and closed by （）
nuts and bolts。new joints。spring force。sealing ring。
问题：
[单选] Each cylinder is closed at the top by a （）, made of a special heat-resistant steel.
cylinder liner。coupling flange。cylinder cover。piston crow。
问题：
[单选] Each cylinder liner on the marine medium speed engines （）.
is usually cooled by sea water。can be replaced when worn out。is in direct contact with the water in the bore of the cylinder。can t expand when heated。
问题：
[单选] Each journal and pin should be examined for （） and grooving.
bridges。recesses。rears。ridging。
问题：
[单选] Each piston stuffing box is provided with two sealing rings and three（）
packings。piston rings。distributor rings。scraper ring。
问题：
[单选] Either a low injection pressure or a leakage of piston rings is able to lead （）.
a high exhaust temperature。a high smoky exhaust。a high output。a high compressio。
问题：
[单选] Emulsion oils and sodium nitrite are both approved additives, but the latter cannot be used if any pipes are （） or if any soldered joints exit.
chromed。welded。galvanized。bolted。
问题：
[单选] Emulsion oils and sodium nitrite are both approved additives, but （） cannot be used if any pipes are galvanized or if soldered joints exist.
the latter。latter。former。the former。
问题：
[单选] Engage the flywheel with the （）.
turning gear。motor。driving gear。driven gear。
问题：
[单选] Engine （） refers to the relative time of position of crank, at which each operation during the cycle is commenced and is completed.
timing。power。firing order。dead center。
