anything也可以用在陈述句当中的,表达的意义和something略有不同.anything是“任何”,something是“有些”.初中的教材可能是为了便于学生记忆,一开始接触这两个词就强调一个用于肯定,一个用于否定.这是片面的,你可能就是受其影响.在一定的语境下,something也可以出现在否定句.比如：There is something in her that I don't like.而anything用于肯定就很常见了：Anything you like,I would like.至于if后面有anything是正常的,甚至比something更常见.比如：If anything happened,I will not forgive myself.就比If something happened,I will not forgive myself.更显得坦诚和真切.
要是对你有帮助别忘了给我设为最佳哟!