Who can tell me that the sentence which I wrote is right or wrong?语法上有什么错误么?With a heard work,we must have a better repay!And we should think of ourselves that why we should study hard!

Who can tell me that the sentence which I wrote is right or wrong?语法上有什么错误么?
With a heard work,we must have a better repay!And we should think of ourselves that why we should study hard!