51.It’s been two years since I stopped doing competitive sports. → I haven’t _______________________________________________________. 52.I have never met such a beautiful girl before. → It ______________________________________________________________. 53.He has worked for this company for more than 15 years. → He started ________________________________________________________. 54. The train has left for one hour. → __________________________________________________________ ago. 55. I last saw Scott last Sunday. → I have ______________________________________________________________.