Here are the possible completions for the sentences based on the context provided:

16. She doesn't usually stay up so late. → She's not used **to it**.
17. It's not a habit of mine to sleep in the afternoon. → I'm **not used to it**.
18. The house seemed to have been unoccupied for several years. → It looked as if **it had been abandoned**.
19. The children should start doing their homework now. → It is time **they did**.
20. Fares will be likely to go up again this summer. → It looks as if **they will increase**.
21. I think the City Council should do something about the city's traffic problems. → It high time **they did something**.
22. We'd better buy a new cooker. → It's **about time we got** a new one.
23. I had better get back to work. → It's **time to get** back to work.
24. I think it may rain. → It looks **like it might**.

Feel free to ask if you need any further assistance!