Составить 5 предложений с новыми идиомами на английском языке

1. I only had a little bit to eat this morning and now I feel awfully hungry.

2. Rick is aware of the fact that he is but a little frog in a big pond in this huge company.

3. Solving math problems is a piece of cake for him.

4. My neighbour is a real gaga, she can not remember my name!

5. He abandoned himself to despair.