Use the correct forms of the verbs in brackets to complete the sentences.
1. Next year we (build) _________ a house overlooking the lake.
2. Spring is coming, so we (celebrate) _________ the Ban Flower Festival soon.
3. If you have a chance to travel on a dogsled, you (never forget) _________ it.
4. If I (be) _________ free to choose a topic, I will give a presentation on Alaska.
5. Unless you try, you (never know) _________ if you can play football.