8. There isn't any milk in the glass.

• We use "isn't" because "there" refers to a singular amount (no milk).

9. Don't throw trash over there.

• We use "don't throw" because it's a negative command.

10. There is a little oil in the bottle. We should buy some more.

• We use "a little" because it indicates a small amount.

11. How many fruits does your father produce?

• We use "how many" because "fruits" is countable.

12. What about having a cup of coffee?

• We use "having" because it suggests an action (drinking coffee).

13. How many floors are there in your school?

• We use "how many" because "floors" is countable. We use "are there" because it's the question form with "there."

14. Is he bad at Physics?

• We use "at" because it refers to a skill or subject.

15. Whose book are you reading? It's Mary's. It's an interesting English book.

• "Whose" asks about possession. "Interesting" describes the book.

16. He doesn't go jogging often.

• This is the most natural way to say that he doesn't jog frequently.