their birthdays only come _____ four years是填each,every还是once

their birthdays only come _____ four years是填each,every还是once Because February29th birthdays come only every four years,my how often is the Olymic Games held?是each four years 还是 every every four years 和each four years哪一个对 elections _______ every four years and congress meets once a the Olympic games are held___(each/every)four years The Olympic Games ____ held every four years.空格处填is还是are呢? held only once every 10 years 的中文意思是什么? BE HELD EVERY 4 YEARS be held once for four years every four和once four的区别 During these years,the school had only four teachers,each of Four years,I only love