spontaneousadj.自发的,自然的,本能的;自然产生的
spontaneous mine自燃矿井
spontaneous fight自发斗争
spontaneous voice自发语态
spontaneous route自发路径
spontaneous light自发光
spontaneous labor顺产
spontaneous crimp自发卷曲
spontaneous tumor自发性肿瘤
spontaneous cycle自然周期
spontaneous sleep睡眠
"this shift occurs spontaneously"
"he spoke ad lib"