a head-to-head contest的用法和样例：
- It costs about $12 a head to eat here.
- Can grand bazoo cause a head to ache?
- A head to head discussion of issues between candidates. Debates represent opportunities for candidates to showcase their personalities, policies, and ideas? Or complete lack thereof.
- You can't go head to head with them.
- The pimple came to a head before bursting.
- He took it into his head to become a politician.