1. If the polar ice-caps (melt)____________completely, sea levels worldwide (rise)__________ about 60 meters. 2. We should avoid (buy)___________frozen foods because their packaging is mostly plastic. 3. A thick smog (settle) __________ over New Delhi since winter (begin)_________. 4. Look! The concert (start)_________ at 7 p.m. and (end)___________ at 9 p.m. 5. To preserve natural habitat, the government (establish)____________ six national parks so far. 6. Do you have difficulty (understand)______________ your Australian friends? 7. The 12th English Teaching Conference (take place)_____________ on 5-12 June. 8. c 9. She (recognize)_____________ the warning signs that she (learn)____________ in a school on tsunami two days before. 10. By the time the firefighters (arrive)___________, the fire (already destroy)____________ over 50 hectares of pine forests.