2)
1. extinct
2. pollution
3. climate
4. live
5. habitat
6. hunt
7. swim
4)
1. Is the climate changing? Yes, it is.
2. Are tigers becoming extinct? Yes, they are.
3. Are you talking to Billy? No, I'm not.
4. Is the female bear protecting her baby? Yes, she is.
5. Are we learning new vocabulary? Yes, we are.
6. Are your friends running in the park now? No, they aren't.
7. Is Jack looking for his book? No, he isn't.