Find and correct one mistake in each sentence.

1. I have never seen a film by Coppola until I took an American cinema class.
2. Have you trying to call me for long? My phone was switched off.
3. Edward has been practised t'ai chi for six years.
4. I am only heard her lecture once, but she seems very knowledgeable.
5. Sara has being to London twice, and now she wants to study there.
6. I have ever visited the British Museum, but I'd love to go sometime!
7. Stephanie have heard enough of the lecture to know she wasn't interested, so she decided to leave.
8. My mother has been worked on her doctoral thesis for several years.
9. James was only been at our school for a month before he was named head boy
10. They speak so fast in this film that I had only understood about half of the dialogues.