1. What do you usually do after school?

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?)

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.

1. All of the answers are grammatically correct and commonly used, but the choice depends on the context and who the speaker is referring to.

- "I always go to an academy" implies that the speaker goes to any academy, without specifying a specific one.
- "I always go to my academy" implies that the speaker is referring to a specific academy that they belong to or are enrolled in.
- "I always go to our academy" implies that the speaker and the person being spoken to are both part of the same academy.
- "I always go to the academy" is a general statement without specifying any particular academy.

2. "I have a father, a mother, and a sister" is correct because it uses 'a' before each term to indicate that the speaker has one of each.

3. "I have Father, Mother, and a sister" is not commonly used. It is grammatically incorrect because 'Father' and 'Mother' are not proper nouns and should not be capitalized in this context. It is more natural to use 'a' before each term to indicate one of each.

4. "I have a father, a mother, and no brothers and sisters" is correct. The statement states that the speaker has a father and a mother, but no siblings.

5. "I have a father and a mother. I am an only child" is correct. The statement indicates that the speaker has one of each parent, and they are the only child in the family.

6. "I have a father and a mother. I am an only daughter" is correct. The statement indicates that the speaker has one of each parent and they are the only daughter in the family.

7. "I have a father and a mother. I have no brother and sister" is correct. The statement indicates that the speaker has one of each parent and no siblings.

8. "Is that really grandmother?" is not grammatically correct. The correct form would be "Is she/that really my grandmother?" or "Is she/that really your/our grandmother?" depending on the context.

9. "Is that really Grandfather?" is not grammatically correct. The correct form would be "Is he/that really my grandfather?" or "Is he/that really your/our grandfather?" depending on the context.