My life has been music, and a constant search for it has been the mainspring of my life.
我为音乐而生，对音乐的不懈探索已经成为我生活的动力。
《柯林斯英汉双解大词典》
2
You begin to understand what actions were the mainspring of the story.
你开始明白什么是这个故事的主要情节了。
《柯林斯英汉双解大词典》
3
In the early 1400s came the invention of the coiled spring or fusee which maintained constant force to the gear wheels of the timekeeper despite the changing tension of its mainspring.