自然界水循环的意义？
参考答案：水通过不断循环转化使水质得以净化；水通过不断循环水量得以更新再生；维持生命繁衍与人类社会发展；维持生态平衡。
His father Beijing. He is staying there for two days.
A．is leaving
B．is leaving for
C．is going
D．is
毒物的脂/水分配系数低提示毒物易于
A．被机体吸收B．在体内蓄积C．被肾排泄D．被机体代谢E．与血浆蛋白结合
