Task 4. Each sentence has one mistake. Write the correct sentences. 1. I became interested in science after I have taken part in a school science project.
2. The Montgolfier had presented their first air balloon in 1783.
3. He went on a long holiday after he finished his studies.
4. What did they see while they flew?
5. What was you doing last night at 8.00 pm?
6. They became famous they had made their first invention.
7. I had been working as a teacher since many years.​