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.
I bought two books: a new one and an old one. -Я купил две книги: новую и старую.
Is this your dog? No, this one is not mine.-Это ваша собака? Нет это не моя.
Which jeans will you wear? These (ones) or those (ones)? -Какие джинсы ты оденешь? Эти или те?
These are not your keys. The ones on the table are yours. - Это не твои ключи. Те, которые на столе — твои.
The ones on the floor. - Те, что на полу
the one I bought today. - которую я сегодня купил.
He will wear the write one. - он наденет белую
I prefer the music one.- я предпочитаю музыкальный.
The one next to the baker's- В том, который возле булочной.