()以上党政机关公务接待管理部门负责管理本级党政机关国内公务接待工作,指导下级党政机关国内公务接待工作。
A、乡镇(街道)
B、县级
C、地市级
D、省部级
参考答案:B
There is a piece of work.It takes Mr.A alone 20 days to finish,and Mr.B 30 alone days to finish.It takes them( )days to work together to finish the work.
A.10
B.12
C.15
D.50
高压汞灯关闭后不能再立即点燃。