I am in Year 7 at Walker School前面为什么用in而后面用at?

I am in Year 7 at Walker School前面为什么用in而后面用at? i am in year 7 at walker school是什么意思? I am in Year 7 at walker "I am in Form One at Walker School,"什么意思 求解英语连词成句:I,in ,Two,School,Form,Walker,am,at I am in Year 8 at Woodland School 英语翻译l am in form one at walker school.it is near my house,so 英语翻译l am in Form One at Walker School.lt is near my house,so He is at university in London.I’m in year 7 at YU School.She ----New Year 前面用介词on 还是in 还是at chinese new year前面用in、on、at还是其他 school前面的介词用in还是at