造成循环水各项水质指标均迅速下降的原因有哪些？
参考答案：
①循环水系统有非正常漏水；
②循环水场排污量失控。
If you can't know a new word, ______. [ ]
A. you should look it up in a dictionary
B. I think listening can help
C. you can make a vocabulary list
D. you should take some notes about it
菌斑控制良好的指标是（）。
A．有菌斑牙面数与总牙面数之比小等于10%
B．有菌斑牙面数与总牙面数之比小等于15%
C．有菌斑牙面数与总牙面数之比小等于20%
D．有菌斑牙面数与总牙面数之比小等于25%
E．有菌斑牙面数与总牙面数之比小等于30%
