单项选择题
After resolving the trouble of main power supply, main switch of emergency generator should（）, if power supply is refreshed.
A.be switched off by the duty officer B.be switched on by the duty officer C.be switched off automatically D.be switched on automatically
单项选择题 Emergency generator is installed on board mainly to （）
单项选择题 （）is not installed on the emergency switchboard.
单项选择题 （）belongs to emergency power supplying equipments.
