John went to the school library (to borrow some books.)对括号部分提问( ) did John go to the school library ( 我填的是what do .但是老师说应该是for而不是do .为什么呢?

John went to the school library (to borrow some books.)对括号部分提问( ) did John go to the school library ( 我填的是what do .但是老师说应该是for而不是do .为什么呢?
John went to the school library (to borrow some books.)对括号部分提问
( ) did John go to the school library ( 我填的是what do .但是老师说应该是for而不是do .为什么呢?

John went to the school library (to borrow some books.)对括号部分提问( ) did John go to the school library ( 我填的是what do .但是老师说应该是for而不是do .为什么呢?
for是“为,给”的意思,前面已经说了to borrow some books,后面句子就不能填do,如果填( what ) did John go to the school library ( do ）?他去图书馆干什么 与前面发生冲突