by oneself 好像总是放在句末吧。比如：
The machine runs by itself. 这机器自动运转。
The door opened by itself. 那扇门自动开了。
I painted the room all by myself. 我独自一人粉刷了屋子。
He doesn’t fear to travel by himself. 他不怕独自一人旅行。
They walked off and left me sitting there all by myself. 他们走开了，让我孤零零一个人坐在那儿。
This box is too heavy for me to lift by myself. 这口箱子太重，我自己一个人搬不起来。
请问：by oneself 可以放在句首或句中吗？