单项选择题
The main generators are connected to（）.
A.distribution boards B.section boards C.emergency switch boards D.main switch boards
单项选择题 UMS stands for（）.
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.
