单项选择题
A.the latter B.latter C.former D.the former
Emulsion oils and sodium nitrite are both approved addi...
单项选择题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.
A.chromed B.welded C.galvanized D.bolted
Either a low injection pressure or a leakage of piston ...
单项选择题Either a low injection pressure or a leakage of piston rings is able to lead （）.
A.a high exhaust temperature B.a high smoky exhaust C.a high output D.a high compression
Each piston stuffing box is provided with two sealing r...
单项选择题Each piston stuffing box is provided with two sealing rings and three（）
A.packings B.piston rings C.distributor rings D.scraper rings
