1. The Petrovs have got  a new country house. There is  gas in their house. (Не уверена, но мне кажется, что артикль лишний.)
2. Two days ago Mr. West bought a new computer. The computer is very good. 
3. MIkes uncle has got a dog. He is a very clever dog. 
4. She is crying. What is wrong.
5. My sister is making a cake now. 
6. They often swim. The are swimming now.
7. He is playing the piano now.
8. Listen! Nell is crying. - NO, she isnt crying. She is laughing.
9. I think that they will be come. 
10. Swithc off the radio! I am thinking about our plans.