有一读者问： 有这样一句话：
(1)After only six months he had learned enough to read articles and reports in Russian.
有人说句中的enough是名词，有人则认为它是副词，究竟是什么词，请给以解答。
这里的enough看作名词（有的语法学家则称之为代词或名词替代词或数量词）较妥，因为动词learn在此显然是及物动词。enough用作名词的情况很多，再如：
(2)I have had enough . （enough用作宾语）
(3)Enough has been said. （enough用作主语）
下面一句中的enough才是副词。
(4)Have you played enough ?
因为play在此显然是不及物动词。
