Ответ:

  1. I’m worried I didn’t bring enough clothes for cold weather.
  2. If you do this again, I will have to report it. I’m afraid.
  3. Many people try to give up smoking at some point in their lives.
  4. Please never play with these kids. Stay away from them.
  5. The doctor prescribed a medicine for a headache.
  6. Oil spills can pollute not only water, but also land.
  7. Amur tigers and cheetahs are endangered species.

Ответ: 1 — enough clothes; 2 — will have to; 3 — give up; 4 — stay; 5 — prescribed; 6 — land; 7 — endangered.