every three

every three 是"every three day"还是"every three days"(每三天) every three day;every three days应该用哪一个? every four years等于three? two out of every three=two in three Mr jackson g( ) three classes every day. two or three times every month Every lesson lasts for three hours we have three classes___P.E.every week. every other three days =every four days 对不? every third year与every three years的区别 I read a book every three weeks对every three weeks划线怎么写