17.　 in modern times　　　

16.　 allow doing　　

15.　 allow sb. to do sth　

14.　 compete with/against　　　

13.　 compete in

12.　 from all over the world　

11.　 every few days

10.　 every four years/every fourth year

9.　　　 take part in/join in　

8.　　　 would rather do than do