管网调度的主要作用是什么?
参考答案:管网调度的主要作用:保证各水压控制点的服务水压,满足全地区的正常用水需求,使管网服务压力均衡指挥管网故障的抢修,确保管网安全运行。
With Halloween approaching, there exists a real concern among parents and teachers __________ trick or treating will become a seriously anti-social activity.
A.whether
B.what
C.that
D.how
电工是个特殊工种危险性大,()。