以为：suppose something will happen ,but it don't actually. Ex:我以为你会说汉语呢，原来你不会呀。 想：many meanings：1. think , think of 2.reckon 3would like to .. ect. Ex:1.我想我的爸爸妈妈了。2.我想饭应该快熟了。3.我今天想去公园划船。 觉得：means feel ,"觉得" = "感觉" sometimes , when they are verb form. when "感觉" is noun form,it means feeling,can not instead of "觉得" (Ex:2). Ex:1.今天我“觉得/感觉”很不舒服，是不是感冒了? 2.幸福的感觉真是无法表达。 认为：means deem,someone have itself piont. Ex:1.我认为帮助需要帮助的人，是每个人应尽的义务。 correct my mistake if I have plzz！！

most of time, all of them can be exchanged. ( Ms help's example is great ) let's try another angle to distinguish them! pay more attention to the specific situation and the unique meaning which other phrase don't have: 1. when you express " want, would like to do/have, consider", use "想", "我很困，想睡觉i am sleepy and would like to have sleep", "我想学中文 i would like to learn chinese" 2. when you descibe "you think so, in fact it's not" , use"以为"， “我以为你说谎 i think John lies to me!( in fact John told the truth)”

以为: 1.you think something would happen,but it is not. eg.我以为Alex不会来了。＝I didn't think Alex would come。[but acturally he did.] 2.some as 认为 in Old Chinese. eg.予以为否。＝I don't agree with that。 认为： suggests objective reflection and reasoning。usually be used in written language or formal situation like lecture or academic discussion， eg.我认为这个观点是正确的。 想:in common use 1.similar to 认为，but it's less formal and less for sure and more subjective and emotional.it can be used in both spoken language and written language，especially spoken language. eg.我想你是对的。 2.want,would like to eg.我想看电视。 觉得/感觉： 1.feel eg.我今天觉得/感觉不舒服。 2.similar to 认为，but much less for sure and much more subjective and emotional. eg.我觉得应该是这样。

想,also means " miss" in chinese, EX:很久没见妈妈了，我很想她／想念她． 觉得／认为，they both mean self-point,personal,but 认为比觉得更确定地表达你对某客观事物的看法．例如，我觉得你是对的．it's only a feeling, but if I say "

Alright, let's talk about 以为, 想, 觉得, 认为 and 感觉. Examples: 我____我能赢. 1. 以为:我以为我能赢. If someone says like this, it actually means he or she has lost the game. 2 .想:我想我能赢. I think I can win this game. 想also means "want". 3. 觉得:我觉得我能赢. I have the feeling that I can win this game. 觉得is almost the same with 感觉. 4. 感觉:我感觉我能赢. In my opinion, I can win this game.觉得is almost the same with 感觉. 5. 认为:我认为我能赢.I believe I can win this game. It is the strongest among those words. Dear all, correct my mistake if you want.