held only once every 10 years 的中文意思是什么?

问题描述:

held only once every 10 years 的中文意思是什么?
held only once every 10 years——the World Philatelic Exhibition opened earlier this month in Washing D.C.的中文意思是什么?

十年一届的世界集邮展览于本月初在华盛顿开幕.
World Philatelic Exhibition:世界集邮展览