by choice

基本解释

When he is 25, he is with you only by choice.
而当他到了25岁，就可以选择是否和你在一起。
Of course, for some parents, having just one child is not by choice, but by chance.
当然，对于一些夫妇来说，只生一个孩子并非出于选择，而是出于意外。
ONE fear of European Union members outside the euro, either by choice or because they are not ready to join it, has been that they will be cut out of the big decisions being taken in Brussels.
不管是出于选择也好还是由于根本就不打算加入也好，欧元区外的各欧盟成员国担心的是布鲁塞尔方面在做重大决策时，将对他们不予以考虑。

They did so by choice or because of financial need or both.
He was a hobo by choice: As a little boy, he'd seen a hobo come up to ask his mother for a piece of pie and she had given it to him and when the hobo went off down the road the little boy had said, "Ma, what was that fellow?" "Why, that's a hobo."
他是自愿成为流浪汉的：,当他还是个小男孩的时候，他见过一个流浪汉向他妈妈,要一块派，他妈妈给他了,于是当流浪汉离开的时候小男孩就问，“妈妈，那个家伙是谁“，“是个流浪汉“
耶鲁公开课 - 1945年后的美国小说课程节选
And x0 I'm going to reduce to 0 by choice of my origin being here.
0 等于零,因为我把原点取在这里
耶鲁公开课 - 基础物理课程节选

By heritage and by choice, the United States of America will make that stand.
CENTERFORSECURITYPOLICY: UN told to join US or become irrelevant