Ex. 5 Fill in the article (a/an, the) where it's necessary: 1. ... Mark Twain is famous for his book "The Adventures of Tom Sawyer" 2. Smiths have... dog and ... cat. 3. Is this your ... friend?" "No, it isn't my ... friend, it is my sister" 4. This is ... tree. ... tree is green. 5. What's ... highest mountain in the world? 6. He lives in ... Paris. 7. He is ... economist. 8. ... Earth goes round ... Sun. 9. We celebrate New Year on ... 31st of... December. 10. It is washed by the waters of... Atlantic Ocean. 11. Are you studying foreign languages at school, like ... French? 12. ... Moscow is on... Moskva River.