foolish、silly、stupid、simple与dull这些形容词都可表示“愚蠢的、笨的、傻的”之意。
foolish : 一般指人的无头脑、愚蠢，或缺乏常识与判断力，或指行动的愚蠢可笑。
- That was a rather foolish thing to do.
做那样的事可真是蠢。 - She was afraid that she would look foolish if she refused.
她怕如果拒绝会使自己看起来像个傻瓜。
silly : 口语用词，可和foolish互换，但语气稍强，常含贬义。侧重指人的言行不合常规或不理智，强调单纯、低能和糊涂。
- Don't do that, you silly boy!
不要那么干，你这个傻小子！ - a silly mistake
愚蠢的错误 - It was silly of you to go out in the sun without a hat.
你不戴帽子顶着太阳出门真是太傻了。
stupid : 多指人或行为的愚蠢，尤指先天智能低下，或因某种原因失去正常的反应或感觉。有时也可与
- She was really stupid to quit her job like that.
她就那样辞掉了工作，简直是愚蠢透顶。 - Whose stupid idea was it to travel at night?
晚上赶路是谁的馊主意？ - He now thinks that retiring early was a stupid thing to do.
他现在认为提早退休是件愚蠢的事。
simple : 强调头脑简单或缺少智慧。
- He was simple, but harmless.
他有点儿傻，但不会伤人。
dull : 指对问题理解迟钝，缺乏灵敏机智头脑，可能是先下智力低下，也可能因疲倦或健康不佳所致。
- a dull pupil
脑子迟钝的小学生
