一、fool的用法
1. 用作名词，表示“傻子”，通常为可数名词。如：
I do feel a fool. 我的确觉得自己是个傻子。
但是，在be fool enough to do sth结构中，fool具有形容词的性质，不可数，其前不用冠词。如：
I was fool enough to believe him. 我竟然相信他，真够傻的。
He was fool enough to tell them everything. 他真傻，把一切事情都告诉他们了。
2. 用作动词，表示“愚弄”“欺骗”，总是及物的。如：
She fooled that man. 她骗了那个人。
要表示“欺骗某人做某事”，可用fool sb into doing sth，习惯上不说fool sb to do sth。如：
I was fooled into believing their promises. 我被骗得相信了他们的承诺。
二、foolish的用法
1. 比较同义句型：
It was foolish of her to say such a thing.=She was foolish to say such a thing. 她说出那样的话来，真是太蠢了。
He was foolish to leave his car unlocked.=He was so foolish as to leave his car unlocked. 他真傻，车都没有锁。
2. foolish, stupid, silly的区别：foolish指无头脑，缺乏常识或判断力，相当汉语的“愚蠢”；stupid指智力、理解力或学习能力很差，相当汉语的“笨”；silly指头脑简单，傻头傻脑或令人发笑，相当于汉语的“傻”。如：
She is a silly woman, but not a stupid one. 她是个头脑简单的女人，但不能算笨。
