Change the following sentences into tag questions according to the model.
Model: The climate of the British Isles is affected by the Gulf Stream, isn’t it?
1. Summers are not so warm as in the rest of Europe, are they?
2. Spring is the season when nature returns to life, isn't it?
3. There are periods of sunshine, aren't there?
4. The sky is suddenly overcast with low black clouds, isn't it?
5. After the thunderstorm the air is remarkably fresh, isn't it?
6. Autumn is the season of mists, isn't it?
7. A spell of sunny weather in October is called an Indian Summer, isn't it?
8. On a frosty morning the country is covered with hoarfrost, isn't it?
9. It is freezing hard, isn't it?
10. The rivers and lakes are frozen over, aren't they?