an official letter

• 公函

an official letter的用法和样例：

例句

1. She received several official letters this morning.
   她今天早晨收到了几封公函。
2. For this reason, it is improper for a notarial agency to directly issue an official letter or allow notaries make a video telephone attestation at the request of a foreign court.
   因此，公证处不宜应外国法院要求直接出具公函并由公证员在可视电话上作证。