(1)be +adj +enough to do sth 足够…做某事 eg :I am old enough to go to school . (2)enough 副词（修饰动词）eg:He runs fast enough . (3)be +adj 反义词enough to do sth =too …to =so that 引导的结果状语从句 太……以至于不能…… 再答： （3）的例句：He isn 't old enough to go to school .=He is too young to go to school .=He is so young that he can't go to school .
