7、 anyoneenteredthetrain.Theemptyseatswere(21) andthetrainwhistled(鸣笛声)tomove.Anoldmanwithayoungboyagedaround15hadtheirseatsjustnexttothefriends’group.Theyoungboywasso(22) toseeeverything.Hecheered,“Dad,thetrainismovingandthethingsaremovingbackward.”Hisfather(23) an