He was doing it all by himself.

全都是他独自一个人干的。

《柯林斯英汉双解大词典》

He lives all by himself.

他独自一人生活。

《牛津词典》

He managed to repair the car by himself.

他自己设法修了汽车。

《牛津词典》

He was trying to fly around the world by himself.

VOA: special.2009.03.18

Maybe there is no music, so it's just kind of dancing in the middle of a cookie sheet all by himself.

可能会没有音乐，也许只是在众多饼干人中间,单纯地跳舞。

哈佛公开课 - 计算机科学课程节选

Well, the answer is, in the traditional view, is that he was never meant to stand by himself.

答案在于,在传统观点看来,就是一个士兵从不孤军奋战

耶鲁公开课 - 古希腊历史简介课程节选

It is more about the timing than whether he will be doing it by himself.

FORBES: Safety Matt Elam Is Only Top Prospect To Enter NFL Draft Without An Agent

All the students left the music room, but my brother stood there all by himself.

NPR: Literature and Lullabies from the 'Axis of Evil'

The only other individual nearby was a dozen spaced tables away, by himself, standing upright.

NEWYORKER: Good People