题目

天花病人痊愈后，一般不会再得天花病，这种免疫是                                           （   ） A．特异性免疫                    B．非特异性免疫  C．计划免疫                      D．不能确定 答案：A  — What made Bill so angry? —____________. His girl friend promised to come at 8:30, but she hasn’t come yet.A．Having kept waitingB．Being kept waitingC．To be kept waitingD．He was kept waiting