高三数学教学网

　　注意：a dozen eggs 十二个鸡蛋 two dozen eggs

　　a dozen of these eggs 一打这种鸡蛋

　　dozens of eggs 许多鸡蛋

　　7. every four years 每四年;每隔三年 every fourth year 每第四年

　　every other year 每隔一年 every few years 每隔几年

　　8. take part in = join in = participate in 参加

　　attend 出席 join sb (in doing sth) 和某人一起做某事

　　9. compete in 参加(竞赛) compete against/with 与…相对抗 compete for 为…而竞争

　　10. allow /permit/forbid sb to do sth 允许/禁止某人做某事

　　allow/permit/forbid doing sth 允许/禁止做某事

　　Nothing is permitted; everything is allowed. 一切都不(明文)准许;但也不(明文)禁止。