单项选择题
The main engine is cooled with fresh water （）is added suitable small quantities of chemicals to prevent corrosion.
A.in which B.on which C.to which D.by which
单项选择题 （）during the last repair?
单项选择题 Hardly had the engine started （） the temperature of the cooling water suddenly rose up to 40℃.
单项选择题 The term “moderate speed” was previously interpreted as meaning a speed which would enable a vessel （）within half the range of visibility.
