Ответ:

a

1. 10 years

2. an electric heater

3. 3 or 4 different kinds electric heaters

4. and this is our best electric heater. it costs a lot of money, but it saves half of your electricity and electricity is very expensive now, isn't it?

5. yes, it is very expensive

6.yes they will

b

cold

c

5, 1, 4, 6, 3, 2