Hi Bella thank you so much for doing your homework. ^_^

1.I'm Korea citizen
Correct: I'm Korean citizen.
>> Korean pertains to the people who are living in Korea.

2.I'm library member
Correct: I'm a member of that library.

>> Don't forget to use a period ( . )after your sentence.

3.I really respect my teacher
Correct: I really respect my teacher.
>> Don't forget to use a period ( . )after your sentence.

4.I will treat for my grandma
Correct: I will treat my grandma nicely.
>> Treat means your behaviour towards someone.

5.we should follow teacher's teach
Correct: We should follow our teacher's teaching.
^o^ ?´?o?´? ?´¨?.?´¨? (^?´?^)