(0) Jay and Jane / practise / their dance / already.
Jay and Jane have already practised their dance.
1. Polly/ her ballet dance/just / perform.
Polly has just performed her ballet dance.
2.  Ron / his costume / yet / prepare,
Ron hasn't prepared his costume yet
3.  the children/flowers/yet/buy?
Have the children bought/lowers yet?
4.  the children /peopleto the concert/ vet/ invite?
Have the children invited people to the concert yet?
5.  Andy /the poster/just/finish, Andy has just finished the poster.
6.  Jack / a hat for his tricks / already / bring Jack has already brought a hat for his tricks.
7. The children / what they will do next year / yet / decide.
The children haven't decidedyet what they wilt do next year.