1. by itself 自动地,独自地
（1）The machine will start by itself in a few seconds.
（2）How did the door open by itself?
2. by means of 用,依靠
（1）The water may be carried by means of a pipe.
（2）The stone was lifted by means of a rope and pulley.
3. by mistake 错误地,无意地
（1）She let the news slip by mistake , in an unguarded moment.
（2）She sprayed hair spray in her eye by mistake.
4. by no means 决不,并没有
（1）These truths were by no means self - evident when Galileo first suggested them.
（2）This by no means the first time you have been late.
5. by oneself 单独地,独自地
（1）One is firmly established by oneself.
（2）One should do it by oneself.