以下的股票指数中，属于样本指数类的有( )。
A．沪、深300指数
B．上证成分股指数
C．上证红利指数
D．上证50指数
参考答案：A,B,C,D
______ they had 3 children of their own, the old couple decided to ____ a boy and a girl. [ ]
A. While; adopt
B. Although; deliver
C. However; receive
D. Though; adapt
原水经Na型离子交换软化后水质有什么变化？
