史蒂文斯遭谋杀源于深仇宿怨。Stevens's murder was the result of a deep-seated and intense hatred.他的观点源于他卑微的出身。His views come from his own humble beginnings.严格的职业道德源于清教主义。Out of Puritanism came the intense work ethic....
After the 1960 s, China began to inoculate BCG, pertussis, diphtheria, tetanus, measles and poliomyelitis vaccines.六十年代后, 中国开始在大、中城市接种卡介苗 、 百日咳 、 白喉 、 破伤风 、 麻疹、脊髓灰质炎的疫苗的工作.Recent studies suggested that erythromycin may b...