A:铜片、石墨棒,乙醇
B:铜片、石墨棒,硝酸银溶液
C:锌片、铜片,稀盐酸
D:铜片、铂片,FeCl3溶液
科学发展观的基本要求是坚持全面协调可持续发展。“全面发展”是指( )
胡萝卜素在人体内可以转化为维生素A,常吃富含胡萝卜素的玉米有助于预防( )
I think he should tell the news to his father. (改为否定句)
I ____ tell the news to his father .