单项选择题
A.salinity B.alkalinity C.acid D.sanitary
To avoid scavenge fires occurring the engine timing and...
单项选择题To avoid scavenge fires occurring the engine timing and equipment maintenance （）.
A.should be correctly carried out B.should correctly be taken place C.should carded with care D.must to carry out with great care
To avoid scavenge fires （） the engine timing and equipm...
单项选择题To avoid scavenge fires （） the engine timing and equipment maintenance should be correctly carried out.
A.occurred B.occurring C.not happening D.occur
Those generally used additives for cooling water are ei...
单项选择题Those generally used additives for cooling water are either anti-corrosion oils or inorganic（）.
A.gases B.paints C.inhibitors D.detergent
