by chance是介词短语，意思是“偶然;碰巧;意外地”。相当于 by accident,在句中作状语。英文解释为：
1.anything which was not meant to happen（表示任何不该发生的事，意外发生了。）
2.events that occur in the absence of an intention（在没有意图的情况下发生的事件）
by chance使用例句
By chance they both arrived at the same time. / They happened to arrive at the same time.
他俩碰巧同时到达。
Our life gets better and better not by chance, but by working hard.
我们的生活变得越来越好不是偶然的，而是通过努力。
Silla and Racheal met by chance in a shopping mall.
新罗和瑞秋在一家购物中心偶然相遇。
She got into theater by chance.
她偶尔进入剧院。
Our meeting in hotel was by chance I swear.
我发誓我们在旅馆的相遇纯属偶然。
I heard their secrets by chance.
我偶然听到他们的秘密。
I got this work by chance. I never intended to work for them.
我偶然得到这份工作。我从未打算为他们工作。
After several years of hiding from each other, they met in Paris by chance.
经过几年的逃避，他们在巴黎偶然相遇。