It looks like you have some sentences with prompts for completing or rewriting based on guidelines related to tense and structure. Here are the suggested completions based on the given context:

5. I last read a book on September 20th.
**I haven't read a book since September 20th.**

6. An began to be interested in healthy eating 3 years ago.
**An has been interested in healthy eating for 3 years.**

7. I have never seen that play before.
**It's the first time I've seen that play.**

8. It's two years since I was just in Ha Noi.
**I have not just been in Ha Noi for two years.**

9. I haven't seen this man here before.
**This is the first time I have seen this man here.**

10. The last time I saw Lan was at Tam's birthday party.
**I last saw Lan at Tam's birthday party.**

If you have any more specific requests or need further assistance, feel free to ask!