You are to complete the sentences using the right word. Write down only the word. 1. Environmental protection is an __________ problem. (easy, important, pleasant) 2. Factories pour a lot of __________ into air & water. (a shortage, waste, pollution) 3. What caused the __________ of wildlife? (destruction, poison, population) 4. Many rivers & lakes are __________ . (poisoned, filled, used) 5. Many scientists try to __________ ecological problems. (solve, know, protect)