1. What do you usually do after school?

Question

I always go to an academy.
I always go to my academy.
I always go to our academy.
I always go to the academy.

(Which answer is right and commonly used?)

2. I have a father, a mother, and a sister.

3. I have Father, Mother, and a sister.

4. I have a father, a mother,
and no brothers and sisters.

5. I have a father and a mother.
I am an only child.

6. I have a father and a mother.
I am an only daughter.

7. I have a father and a mother.
I have no brother and sister.

(From 2 through 7, which ones are correct? Are all correct?)

8. Is that really grandmother?
9. Is that really Grandfather?
(Which one is right? Is #8 also correct?)

Answer 1

1 - The fourth one is probably the most commonly used; all are grammatically correct.

2 - 7 --

2 is probably the best.
3 is awkward and not parallel.
http://grammar.ccc.commnet.edu/grammar/parallelism.htm
Scroll down to the second chart to see examples similar to yours.

4 is OK, but would be better with "but" instead of "and" since you are setting up a contrast.

5 and 6 are OK, but the sentences sound "choppy" when they are not joined with a comma and conjunction as the earlier ones are.

7 is OK, but also sounds choppy as separate sentences. Also the conjunction in the second sentence should be "or" not "and."

9 is better than 8; since you are referring to a specific person you call by that term, the capital G needs to be there. If you had written, "Is that really my grandmother?" -- then no capital G.