【多选题】下列关于影响混凝剂混凝效果的因素描述错误的是:
B.
使用硫酸铝作为混凝剂去除水中浊度时,最佳PH值在6.5~7.5之间
C.
由于铝盐和铁盐混凝剂在水中水解时会产生H+,因此水中应有足够的碱性物质缓冲,维持ph值
D.
原水中杂质颗粒尺寸越单一、越小,越有利于混凝
【单选题】听力原文:W: What does the report say about the car accident? M: If the policeman hadn't stopped his car in time, the man might have ended up killing himself and injuring several other people walking on th...
A.
A disastrous car accident happened on the street.
B.
Nobody was injured in that car accident.
C.
Several people were killed in the car accident.
D.
The driver himself got killed in the car accident.
【多选题】( ) 是 “ 十三五 ” 旅游业 发展趋势
【单选题】生态园林绿地建设中应以 植物 为主,其中又以( )的作用最大。
【单选题】下列关于旅游业发展趋向中,不属于“十三五”我国旅游业发展趋势的是 。