自然发生spontaneous generation
任意的，自发的spontaneous
自然阴道分娩spontaneous vaginal delivery
a.自发的；自然产生的spontaneous
自愿呈报制度spontaneous reporting system voluntary
不能维持自主呼吸 Inability to Sustain Spontaneous Ventilation
自发反应spontaneous reaction
吐衄blood ejection and spontaneous external bleeding