9/11
mainly US uk/ˌnaɪn.ɪˈlev.ən/ us/ˌnaɪn.ɪˈlev.ən/
（2001年袭击美国世贸大厦和五角大楼的） 9/11 事件
September the eleventh, written in US style: the date of the attacks on the World Trade Center and the Pentagon in the US in 2001
Since 9/11 there has been more cooperation between Russia and America. 自从9/11事件后，俄美两国加强了合作。