every four和once four的区别the games are hold __years为什么是once four

every four和once four的区别the games are hold __years为什么是once four every和once的用法区别奥运会四年举办一次是：The Olympic games are held every four years.但是能不能说：The Olympic games are held once four years.有没有什么特定的规则呢? four four four FOUR. every four years和every fourth year一样吗? every fourth year和every four years一样吗 every four years和every fourth year一样吗? their birthdays only come _____ four years是填each,every还是once every four years 和each four years哪一个对说明理由 each four days和every four day各自是什么意思,有什么区别? the Olympic Games are held once ___A every four years B .every four year C.every -four -year怎样区分呢?为什么B 不可以呢？Every week 后面也不加s啊？ every four years代表什么 every four years什么意思? 英译中every four weeks every fourth week The Olympic Games are heldA every four years B every four year C every fourth years D every four-years every four days与 every fourth day的区别在语法和翻译上的区别