a head of cranes的用法和样例：
- The President cannot rudely ignore a head of state.
- He that have a head of wax must not walk in the sun.
- A head of white-blond hair resembling tow.
- He dug up a head of celery and gave it to the cook.
- You're not getting up much of a head of steam.
- Be a head,though only the head of a potato.