at school ，不是in the school楼上应该是错的

in school(在学校里)

in the school

at school (英国英语)，在学校、在上课、在求学。例如： I have some other friends at school. 我在学校里还有一些别的朋友。I have lunch at school. 我在学校吃午餐。I have a problem at school. 我在学校有一个麻烦。in school (美国英语) 在学校、在求学。 = at school例如：Did you learn how to borrow yet in school你学会在学校里怎样借东西了吗 In school and at home, my daughter loves to win. 在学校和家里，我女儿喜欢争强好胜。I have many friends in school. 我在学校有很多朋友。