Here are the completed sentences:
- I'm not sure, but my parents might give me a smartphone for my birthday.
- He's not answering his email. He will be on holiday. I don't know.
- There will be enough time to discuss it in class, so let's talk about it on the forum.
- She might be able to phone you. I don't know if her mobile works there.
- I'm sure Amy will post the photos on Facebook so that we can all see them.