-그녀는 그렇게 많이 먹지 않아.

 She doesn't eat that much. ​

-아프지 않아.

 It's not hurt.  -> It doesn't hurt. 

=> Corrected: The sentence is corrected grammatically. 

-난 사과를 좀 사고 싶어.

 I want to buy some apples. ​​