写出下列动物短语的意思
The plan is a dead duck:there is no money.( )
My new car goes like a bird.It runs fairly well.( )
You can talk till the cows come home;you'll never make me change my mind.( )
I smelt a rat when he started being so helpful.( )
They lead a cat-and-dog life ,so they decided to get separated.( )