Choose the correct verb forms.

Dear John,
Hi! How are you?
I've been really busy lately because I ... a Young Inventor's Competition next month. It's at the National Exhibition Center on the 17th August. It ... at 10 am and ... at 6 pm. I ... a presentation of my invention to hundreds of people.
Until then I ... night and day to improve it. I won't tell you now what it is but I think everyone ... surprised. By the day of the competition I think I ... enough time to make it perfect. Do you know I ... on it for almost a year by then?
Well, that's all for now.I hope you can come and see me and my invention.
Write back soon.
Owen