51．A．For                     B．Once                   C．Even if                  D．Although

50．A．not attending        B．taking                  C．not missing            D．passing

49．A．knows                 B．to know               C．know                     D．knew

48．A．hardly                 B．strongly               C．badly                     D．mostly

47．A．on                       B．to                        C．in                          D．of

46．A．those                   B．who                    C．which                    D．whose

45．A．no use                 B．no time                C．no chance               D．no excuse

44．A．what                   B．how                    C．how many              D．why

43．A．wrong                 B．right                    C．stupid                    D．helpful

42．A．pardon                B．repeat                  C．ask                        D．raise