这题怎么错了You must study very hard at school for a student,回答并更正

You must study very hard at school for a student
for改为as
作为一个学生你在学校必须努力学校.
as,作为的意思那That is difficultfor Bob to remember so many words in a short time呢it is difficult for sb to do sth.：（事）对于某人来说很困难。固定短语搭配。而不是that is ....