999
uk/ˌnaɪn.naɪnˈnaɪn/ us/ˌnaɪn.naɪnˈnaɪn/
999 （英国的紧急求救电话号码）
the phone number used in the UK to call the emergency services
a hoax 999 call 打999报假案或搞恶作剧
There's been an accident - dial 999 and ask for an ambulance. 发生事故了， 快拨999叫救护车。