I can not but think so.和I have to think so.的区别?

I can not but think so.和I have to think so.的区别? I think so but i can' i think so和so i think区别 So I think I can i don't think so和i disagree的区别 I Don't think so 与 I think not 用法的区别 为什么“I think I do not should have done so" i think so.but some people not unerrtand I think so.But some people not unerrtand! "I think I can,so I You can,but I don't think so why... Me,too.和I think so ,too的区别