My class is the best class in my school. My class mates helps and co-operate in my difficult situations .My teachers are my mentors who encourage and motivate me to do my best in developing myself. I'm very thankful and grateful to my parents and my principal who gave me this opportunity to study here to become a good student as well as good citizen of the country.

Owns. "One of the pupils" implies a single person or singular noun..so Owns is the apt one.

As I understand you want to understand meaning of the idiom mentioned in the question. Virtue is its own reward means if you are doing something good meaning you are virtuous, you won't long for any reward for this deed, this nature of doing good for others itself is a reward.

1) I am going to marry an heiress. While pronouncing the word "heiress" there is an indication of the vowel "a" in it. Which is why an is used. 2) The report was accepted by a unanimous vote. In this case "uninamous" is pronounced as "yu" which is consonant. So "a" is used.

Is this my family?

First sentence Is incorrect Ans is..My daughter prefers to see a lady doctor

Stays and staying

Sentence : Coming events cast their shadows before.

Finite verb : cast

Has been is changed into have been but there is action completely done so I think that in this sentence would be use Had been but in some cases the verbs and tenses are not changed like has been will remains has been ,have been will remain have been

What is an independent clause? - a clause that can stand alone as a sentence, having a subject and a predicate. Remember that an independent clause has to have a subject and a verb.

Now, your answers: 

2. We wanted to help the man because he is helpless. (try to make it simple).

3. Mother picked up the dishes and placed them on the sink.

4. I am reading a book which my father bought yesterday. 

5. Okay

6. Rahul was delighted with the result after it had been announced.

7. Okay

8. Okay