3. Polar bears are critically ______. If global warming goes from bad to worse, they will soon disappear from the planet. (A) occupied (B) endangered (C) mentioned (D) limited

10. The dirty air, known as smog, is a combination of weather conditions, fumes and smoke from cars and factories and therefore is sure to ______ many serious health problems. (A) bring up (B) give rise to (C) look forward to (D) have little to do with