阴阳者，（）之道也，（）之纲纪。
参考答案：天地；万物
用铜和硫酸铜、银和硝酸银溶液设计一个原电池，电池的总反应的离子方程式是______
负极反应式是______；
正极反应式是：______．
Mike will go abroad tomorrow. I am going to _____ at the airport. [ ]
A. sent him off
B. saw him off
C. see off
D. see him off
