spontaneous

The crowd gave a spontaneous cheer..人群自发地欢呼起来。

My spontaneous reaction was to run away..我的本能反应就是逃跑。

spontaneous combustion自燃

spontaneous emission[电磁学]自发发射

spontaneous abortion自然流产；自发性流产

amplified spontaneous emission放大自发射；放大式自发射

spontaneous ignition自燃

spontaneous polarization自发极化；自然极化

spontaneous recovery自然回复（恢复）；自然痊愈

spontaneous radiation自发辐射

spontaneous magnetization自发磁化；自发磁化强度