原发性慢性间质性肾炎的病因是（）
A.放射线
B.重金属
C.含马兜铃酸药物
D.镇痛药、环孢素
E.巴尔干肾病
参考答案：A, B, C, D, E
根据句意和首字母提示补全单词.
1. Don't w________ water. Please turn off the cock after you wash your hands.
2. Gold, silver and iron are all m_______.
3. It's more and more important for everyone to save e_______ now.
4. Air p_______ is quite harmful to our health.
5.The students from a green school are helping collect waste paper and bottles for r________.
机组启动及正常运行时，凝结水硬度应分别不大于（）
A、3umol/L、20umol/L
B、20umol/L、3umol/L
C、20ug/L、50ug/L
词.