All confirmed cases in the cluster can be directly linked to close and prolonged exposure to a patient during a phase of severe illness.
该群集中的所有确诊病例可直接与长期密切接触处于疾病严重阶段的患者相联系。
2
It is difficult to show that an intervention prevents cancer, given the relatively long induction phase between exposure to an inducing agent and development of disease.
很难说一种干预方式，施予一段相对较长的介于接受诱导剂和诱发疾病之间的诱导治疗期，可以预防肿瘤。
3
Fly on nonstop RoutingsMost accidents occur during the takeoff, climb, descent, and landing phase of flight so flying nonstop would reduce exposure to these most accident prone phases of flight.