Sure! Here are the completed sentences:

1. I have been learning English since 2015.
2. She began teaching English in this school 5 years ago.
3. Ba last visited his parents 2 months ago.
4. How long is it since he last wrote to you?
5. It's the first time we have eaten this kind of food.
6. I have never seen this film before.
7. After he had worked hard for many years, he retired.
8. They haven't cleaned their room for two weeks.
9. When did he last write to you?
10. After travelling across India, they flew on to Japan.

Let me know if you need any more assistance!