I work hard at all my subjects是什么意思?

I work hard at all my subjects是什么意思? I work hard at school. hard at work school I(? At work,I must work hard I work hard at schoo 和 At school Iwork hard work hard at hard I enjoy school and I work hard atI enjoy school and I work hard at all my lesson.A ,am B,very C,much D,really I'm not good at G_______,so i must work hard. chinese is not easy for me ,but i like it very much .i 'm going to work hard at it.请问这句中的work hard at 是什么意思? Tom is trying ___（work）hard at all subjects. All the chilldren work hard at还是work hard on our lessons I'm _____ students.I work hard all dayA a little bitB bit ofC a bit ofD a bit little 英译汉:work hard at work hard at中文 2．I'm pleased to hear of your job offer一all that hard work at school has obviously________.A) paid off B) taken its toll C) made a difference D) shown up work hard in还是work hard at? My brother is good __English ,and I do well __Maths.We all work hard __them.横线上为什么分别填上 at,in,at I work hard at school.So ____(do)my brother