There is _________ in the classroom. We have to call our teacher for help.[ ]

A. someone else              

B. other someone

C no one else                

D. no other someone

检修同期调相机，如调相机有启动用的电动机，还应断开此电动机的断路器(开关)和励磁电流，并悬挂“禁止合闸，有人工作!”的标示牌。