自发

例句：

1. 1. The fire started spontaneously in thefireplace.
   火在壁炉里自发地燃烧起来。
2. 2. He decided to leave without askingfor permission.
   他决定不经请求就离开。
3. 3. The animal was acting instinctively,without any conscious thought.
   动物本能地行动，没有经过思考。