As far as we know, half of Canadian teenagers do not get enough sleep on school nights, _____?

A．do they

B．don’t they

C．don’t you

D．isn’t it

交接双方必须按规定时间在工作现场进行交接。罐笼等提升容器在运行中，一律不准进行交接班，须待罐笼到位停稳，并打定点信号后才准交接。