Son,once you put this picture back together,we can play catc

Son,once you put this picture back together,we can play catch,
do not interrupt me again _until___ you finish.填 unless 可以吗?为什麽?
不可以.因为do not interrupt me again _until___ you finish.=You can interrupt me again if you finish.
do not interrupt me again unless you finish.= do not interrupt me again if you don't finish.