二、单项选择题

70%乙醇洗脱得到( )

A．糖
B．皂苷
C．有机酸
D．生物碱
E．甾体苷元 用大孔吸附树脂分离中药成分时

According to the talk, who owned the receivers in the early days of radio

A．Military communications officers.

B．People who treated radio technology as a hobby.

C．People who lived in big cities.

D．People with an interest in music