Learn 9 common idioms in English, including 'when pigs fly', 'cool as a cucumber', 'like a bull in a china shop', 'be on cloud nine', 'lame duck', 'storm in a teacup', 'make a mountain out of a molehill', 'let the cat out of the bag', and 'put a cat among the pigeons'. Each idiom is accompanied by an example sentence to help you understand its meaning and usage.