“以为” 是 “wrongly think”, like : I thought. actually it is not. “觉得” 是 “I think for opinion” or "I feel". 希望能帮到你。

Shiyao Xu的评论解释得非常到位 哈哈 觉得: To think, eg. I don't think he is coming.(in this case is a prediction) 我觉得他不会来/我不觉得他会来。 以为: I thought.... eg. I thought he wouldn't come.(but he did) 我以为他不会来的。

觉得和以为都是表达个人想法的词，但是以为更强调事实和我本来的想法有差距或者反转。举例来说：我以为他很好。这就是说，他其实不好。In English, the sentence means I suppose he is a good man, but in fact he is not. 希望你能理解。如果我说：我觉得他很好。那就是说I think he is good. 没有反转。 Have fun learning！

认为是 ：自己所积累的知识经验来做出判断。Think it is: the accumulated knowledge and experience to make a judgment. 觉得：只是凭借自我感觉，比较主观，不用需要有什么理论知识。Feel: just rely on self feeling, more subjective, do not need to have any theoretical knowledge.

“觉得”表达的是你不知道事情真相时的想法，“以为”用在当你知道事情真相后，向别人表达你当时想的是相反的，比如“我以为今天会下雨，但是今天没有。”