if you won't do it .i'll get Tom to do it .改为同意句

原句应该是 if you don't do it .I'll get Tom to do it .
if ...not = unless 条件状语从句的从句中只能用一般现在时表将来

同意句是 Unless you do it,I 'll get Tom to do it ,

Tom won't do it until you do it.

I'll get Tom to do it except you do .