1.many people,不是many of people,2.interested in psychological principle.缺个动词.可以用intersted in researching psychological principle(前面有谓语动词are,这次用非谓语动词).principle 用复数,has focused 用have been forcusing on,October,December 逗号去掉 用and代替,把all of them 也去掉,all of them 用错地方了.The rhyme helps many people remember which month of the year have 31 days.这句话改成many people use the rehyme as a tool to distinguish which moth have 31 days whcih moth don't.Organization also makes difference in our ability to remember(结构错,而且少成分),这句话应该改成 Organization also is a significant influential reason that affect our brain's capacity to remeber the moth wich have 31 days and which do not.最后一句第一个 Material that is categorized（画蛇添足而且错误）categorized marerial is easy to remembere than jumbled information（比较2个东西的时候结构保持一致）拉了一点 January,March,May,July,August,October,December,all of them have thirty-one days.The rhyme helps many people remember which month of the year have 31 days.这两个句子中间用连词连接so,therefore