看看这句英文对不对

应该是：
Sports is beneficial to students on campus not only physically but also mentally.

“not only”一定跟着用“but also”的。

in是介词，后边跟名词
not only in physics but in mentality. 或是not only physically but mentally.

写的乱七八糟哦
Sports not only physically but also mentally benefit students on campus .

排比句，第二个in可以省略

not only 与but also 所接的成份结构要相当。