在那家小店里找到那本绝版书真是天大的运气。

Finding that rare book in the small shop was ___a ___stroke ___of ___luck.

买到这场音乐会的最后一张票，感觉真是撞了大运。

Getting the last ticket for the concert felt like ___a real ___stroke ___of ___luck.

在会议上遇到首席研究员是我的运气，这推动了我的项目进展。

Meeting the lead researcher at the conference was ___a ___stroke ___of ___luck that advanced my project.