1. 三者在含义上的区别：foolish 通常指无头脑，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：
He is a foolish young man. 他是个愚笨的小伙子。
You were foolish to believe what he said. 你相信他的话太傻了。
We must put an end to this foolish behavior. 我们必须终止这种愚蠢的行为。
You seem even more stupid than usual today. 你今天好像比平时更加笨了。
I’m not so stupid as to put it in writing. 我不至于蠢到会把它写下来。
Who planted such a silly idea in his mind? 是谁灌输那样愚蠢的思想给他?
She spends her time reading silly romance. 她把时间花在阅读傻兮兮的浪漫硅石故事上。
It was foolish (stupid, silly) of her to say such a thing.
=She was foolish (stupid, silly) to say such a thing.
He was foolish (stupid, silly) to leave his car unlocked.
= He was so foolish (stupid, silly) as to leave his car unlocked.