Use If...Then

In such case, the best way to deny the work is to use "If... Then".

You don't need to deny them right away, but say "If she finish what...what..., I will complete what... what...". In most case, those people will never be able to finish your "If". Then you don't have to complete anything. If your boss ask the progress, show him/her the meeting minutes and say that I am still waiting for her to finish that thinggy.... LOL...