单项选择题
UMS stands for（）.
A.ultra much space B.universal medium system C.unit machined space D.unattended machinery space
单项选择题 Oil mist detectors are usually used on board to detect oil mist density within （）.
单项选择题 A viscosity regulator used for an engine is usually provided in order to （） for an engine burning heavy fuel oil.
单项选择题 A manometer is used to measure （）.
