Big cities are always densely populated. You will never find a city without any plant or factory. They may produce necessary goods, but at the same time they are the main air pollutors in a city. This can become a global ecological problem if we don't invent the way of cleaning the air.
Plants and factories also pollute water in rivers and lakes. A polluted river loses its "population": fish and water grass, and becomes unavailable for rest and fishing.
While I am speaking about factories I don't except that people are the city polluters too. Nowadays every fourth person owns a car, which also pollutes the air. There are some people who drop litter in parks and even in streets. This litter will not disappear immediately.
11 had been teaching 12 got
13 did you see 14 was sleeping
15 had been cleaning
16 was Jill saying -walked 17 was talking
18 had been waiting 19 arrived
20 came 21 had cooked
22 had written 23 realized
24 had been painting 26 took
27 were you talking 28 came
2. I (do not drink) coffee in the evening. I ( drink) coffee in the morning.
3.
Is your friend (doing) his homework now?
4. Does your friend<span> ( go) to school in the morning?
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Учебник кузовлёв перегудова стрельникова 4 класс
1) We’re fishing; saw
2) is watching
3) didn’t hear; was listening
4) holds
5) does the race start
6) did it happen