a letter of authorization的用法和样例：
- I'm writing a letter of thanks to them.
- A good face is a lteter of recommendation.
- If the contract is concluded by the procurement agency on behalf of the purchaser, a letter of authorization shall be provided as an annex to the contract.
- He is fishing for information by a letter of inquiry.
- I hope a letter of admission will be issued to me in due course.
- Within two days I received a letter of acceptance from the manager.