With his parents keeping _________ close watch on him, he has no idea how to have _________

access to the Internet.[      ]

A. /; /      

B. a; /      

C. a; an      

D. /; the

存储器按信息保存方式分类，可分为挥发性和不挥发性存储器两种，（）。

A.RAM是不挥发性只读型存储器

B.RAM是不挥发性随机型存储器

C.RAM是挥发性随机型存储器

D.RAM是挥发性只读型存储器