Answer:
1. The Sun is our main star.
2. He is a man of ability.
3. An old man was drinking tea.
4. This car belongs to my friend. It´s mine.
5. I ask my brother to help me. I ask for help.
6. What is your opinion?
7. A cat is on the chair- Don´t sit there.
8. A lot of birds are in the cage.
9. There are not any sick animals in the zoo! It´s a good place.
10. There is not a good restaurant in town.
Step-by-step explanation:
1. The Sun is our main star. ( definite article is missing)
2. He is a man of ability. ( article is missing)
3. An old man was drinking tea. (article is missing)
4. This car belongs to my friend. It´s mine. (Demonstrative and Possessive Pronoun was missing)
5. I ask my brother to help me. I ask for help. ( addition of correct Prepositions)
6. What is your opinion? ( no error)
7. A cat is on the chair- Don´t sit there. ( auxiliary verb and spellings of sit)
8. A lot of birds are in the cage. ( auxiliary verb )
9. There are not any sick animals in the zoo! It´s a good place. ( incomplete sentence structure)
10. There is not a good restaurant in town. ( Demonstrative pronoun and auxiliary verb were missing)
The given sentences had some grammatical errors which are indicated in the brackets gives and rectified.