C-7:cool one's heels 久等
A:Hurry up, or you'll be late again.
A:快点,不然你又要迟到了。
B:I'm coming.
B:来了。
A:You can't keep them cooling their heels each time.
A:你不能每次都让他们空等。
B:Don't worry, I won't this time.
B:放心,这次不会了。