Metaphors or not

Hello everyone, for my homework I have a task in which I have to identify if these are metaphors or not. Could you please tell me which ones are metaphors, and which ones are not.

1. It's raining cats and dogs.
2. He's got a heart of stone.
3. I'm under the weather.
4. Keep a weather eye.
5. Pick up your ears.

You have miscopied no 5 - I'm pretty sure your teacher gave you the phrase "prick up your ears", not "pick up". And if you read the notes you made when your teacher explained to you what a metaphor was, or even look up the word in a dictionary, you'll easily be able to figure out which of these phrases are metaphors.