请老师帮忙修改一下短文

    Newton is one of the greatest scientists in the world .One day he read book under a tree .At that time an apple in the tree fell down to his head .If I was him ,I would fell very sad snd think I was too unfortunate .But through it Newton discovered gravity .He thought why the ripe apple fell down the ground in stead fly raise and what if the ripe apple fly raise snd so on .Finally through hie exploration he diacovered gravity .I think there is much point on didn 't giving up .We should learn from him .

谢谢！！