(1) priceless意为“无价的，极其珍贵的”。

• A lot of priceless historical relics were reported to have been excavated recently in an ancient tomb of the Han Dynasty.
  据报道，最近在一座汉代古墓中发掘出大量珍贵的历史文物。
• He was said to own many priceless antiques.
  据说，他拥有许多珍贵的古董。

(2) invaluable意思是“价值无法估量的，无价的，珍贵的”，与priceless同义。

• These manuscripts are invaluable to scholars and should be in a museum.
  这些手稿对于学者是无价之宝，应放入博物馆。
• We should thank him for his invaluable help.
  我们应感谢他的宝贵帮助。

(3) valueless和worthless意为“没有价值的，无用的”(另见“tawdry...”条目)。

• The stamps he bought proved to be worthless .
  他买的邮票，原来没什么价值。
• The necklace of hers is made of brass. It is completely valueless .
  她的项链是黄铜的，根本没有任何价值。