1 Zoos play an important conservation. 2 Cars burn/emit petrol. 3 Animals should live in their natural ecology/ habitat. 4 Acid rain causes/poisons trees and plants. 5 He made off/up the whole story. 3 Complete with the present perfect continuous form of the verb in brackets. 1 He ........ (work) here for over ten years. 2 Jill ........ (swim) in this lake since she was a child. 3 How long ........ (you/take care) of this injured bird? 4 They ........ (study) very hard for their exams. 5 My parents ........ (donate) to WWF for a long time. 6 The government ........ (try) to reduce pollution for years. 4 Fill in: have to, don't have to. 1 I ........ do it tonight. It's urgent! 2 You ........ water the plants. I've done it. 3 Do you ........ leave so early? 4 He ........ go to school. He's ill. 5 You ........ pay £10 to b e a member.