five of these sentences have mistakes in perfect tense. Find the sentences and correct the mistake.
1. My pen friend writes that he has just come back from London. 2. Last week he wrote to me that he has stayed in London for about a week. 3. We knew that our friends had enjoyed the film. 4. Why didn't you tell me that you and Poul have met before? 5. Look! I had made some coffee for you. 6. - Where is Mum? - She just gone out. 7. Did father tell you that he has bought some tickets to the cinema? 8. I read in the newspaper that the President had left the country. 9. She known that i have told her the truth. 10. Mother says that she had always wanted me to be a doctor.

2. Last week he wrote to me that he had stayed in London for about a week. 4. Why didn't you tell me that you and Poul had met before?  5. Look! I have made some coffee for you. 6. - Where is Mum? - She has just gone out. 7. Did father tell you that he had bought some tickets to the cinema?