1. went
I went to school.
(This sentence is correct)

2. will
I will go market.
> I will go to the market.
~Article "the" is also used to be specific of something.

3. going
I'm going my friend house.
> I'm going to my friend's house. 
~ Subject and Verb Agreement (If the subject is singular, the verb must also be singular; If the subject is plural, the verb must also be in plural form.)

4. ate
I ate chocolate.
(This sentence is correct.)

5. asked
I asked my teacher.
(This sentence is correct.)

6. cooked
My mom cooked lunch.
> My mom cooked for lunch.
~For is also used because of something.

7. walking
I'm walking.
(This sentence is correct.)

8. playing
My brother is playing with his friend.
(This sentence is correct.)

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                                        A big smile for Kelly! ^^

    Wow! Most of your sentence are correct. Keep it up, Kelly. I could see you improvement this term. I am very happy that you are somewhat aware now of your errors. 
    Keep practicing and always study your corrections. Take care always and see you in the class.

   ~Teacher Cassie