离子选择性电极的电极斜率的理论值为（）。25℃时一价正离子的电极斜率是（）；二价正离子是（）。
参考答案：2.303RT/nF；59.2mv；29.6mv
The principal is not here, and you'd better call him ______ 3 p.m. ______ 5 p.m. tomorrow. [ ]
A. between; and
B. from; and
C. from; to
D. between; to
简述观赏鱼有哪些分类？
