priceless

这个古老的花瓶是一件无价之宝。

This ancient vase is a ___priceless treasure.

环游世界是一次宝贵的机会。

A trip round the world is a ___priceless opportunity.

在那个困难的项目中，他的建议是无价的。

His advice was ___priceless during the difficult project.