单选题

It is ______ waste of time for young men to devote themselves to playing computer games on______Internet only for ______ pleasure.

A /; the; /

B the; the; /

C a; the; a

D a; the; /

解析：
句意：年轻人为了玩乐沉迷于电脑游戏是在浪费时间。a waste of tim固定搭配，意为“浪费时间”。on the Internet也是常用表达法。pleasure是不可数名词，其前不用冠词。故答案是D项。