"The Australian government are useless . If Combet opens his mouth, would you believe him????. He is not a scientist!!! ... he is just a bit of a mouthpiece, for a bit of rubbish"
Greg Combet has university degrees in Mining Engineering and Economics, as well as a graduate diploma in Labour Relations and the Law.
He is obviously better qualified than you are. Your sentence "The Australian government are useless" is incorrect. It should have been "the Australian government is useless".
So, who is "just a bit of a mouthpiece, for a bit of rubbish" ?