Các loại nguồn rộng của ô nhiễm không khí trong một khu vực đô thị bao gồm: (i) vận tải (động cơ xe cộ và đường sắt), (ii) cơ sở thương mại, công nghiệp (iii), (iv) trong nước nấu ăn / sưởi, (v) chạy trốn bụi và đốt sinh khối (vi). Cũng có thể là một số nguồn duy nhất hoặc cụ thể trong một khu vực cụ thể. Thủ tục và độ tin cậy của phát thải hàng tồn kho thường xuyên nguồn điểm, khu vực và dòng được thành lập. Tuy nhiên, xác định và định lượng các nguồn phát thải không bền. | Modals 3 Read about what has happened on a camping trip. Two boys are camping with their families near a lake. One day they find an old boat and decide to row out to an uninhabited island. They explore the island until suddenly they realise it s getting dark. They run to find the boat but it s gone. Here are some of the things their families say when they don t come back. 1 There can t be much to eat on the island. 2 Someone may have noticed them rowing across the lake. 3 They could be stuck there for days. 4 A fishing boat might see them. 5 They must have forgotten how late it was. 6 They must be getting scared. 7 There may be a cave or hut they can shelter in. 8 The boat could have sunk. 9 Someone may have taken the boat. 10 They can t have tied the boat up properly. Write the number of the sentences with their meanings a or b. a I feel certain about this. .1. b I think this is possible. Fill in the gaps with a modal verb and the correct form of the verb in brackets. 1 Jenny s . . be a doctor because he s only 18. 2 Samantha said she d go for a swim as soon as she reached the seaside so she . swim in the sea right now. 3 I don t seem to have my wallet. I. leave it at home because I paid for my train ticket. 4 A I left Camilla a message on her answerphone but she hasn t rung yet. B She. not listen to it yet. She usually has a shower as soon as she gets home from work. 5 A I found this watch in the changing rooms. B It. be Peter s. I think he s got one like that. 6 I can t make the video recorder work. I. do something wrong. Where are the instructions 7 I can t think what s happened to Annie. She left home hours ago so she . be here by now. 8 These football boots don t fit me any more. My feet. grcnv . 123 9 He remembers when there were fields here instead of houses so he . be very old. 10 A I don t really like James. Why did you invite him tot come anyway. He said he wasn t 5 B Don t worry. He. sure what his plans were. Read this police report .
