I'm working on the statue , but most of my skilled builders died
and no one can work on it except skilled builders
so now i need to train builders , but on what ?
i have finished building the 3 huts+the clothing hut
and i have cleared rubbles and leaves , so no more building projects !! so how can i train builders now?

((and if i left the statue without work for few days will i lose the progress? ))

You won't lose progress. You can train builders(you only need trainee level) by dropping them on huts. They will say fixing or repairin hut. Each time you do this they will gain skill until they're up to trainee level. Then you can drop them on the statue and they'll work on it.

OK thanks a lot