这件艺术品是独一无二的杰作。

This artwork is a ___one-of-a-kind masterpiece.

他喜欢独处，经常一个人去徒步旅行。

He enjoys solitude and often goes for ___one-person hiking trips.

我们需要与项目经理进行一次一对一的会议来解决这个问题。

We need to have a ___one-on-one meeting with the project manager to solve this issue.