她在厨房里打翻了热汤，幸好没有发生严重事故。

She spilled hot soup in the kitchen, but fortunately there were no serious ___accidents.

这次偶遇纯属意外，没想到会在这里遇见你。

Running into you here was a complete ___accident; I never expected to see you.

我在街上遇到了多年不见的老同学，纯属偶然。

Meeting my old classmate on the street was a complete ___accident.