a picture stuck onto wood or cardboard and cut into pieces of different shapes that must be joined together correctly to form the picture again

If you're suffering from anxiety, try knitting, painting, or doing a jigsaw puzzle. 如果你感到焦虑，可以尝试编织、绘画或做拼图游戏。

a complicated or mysterious problem that can only be solved or explained by connecting several pieces of information

All scientists can do is keep looking at all the facts they've collected, hoping one day to fit thousands of pieces of this historical jigsaw puzzle together. 科学家们能做的就是不断审视他们所收集的所有事实，希望有一天能通过将几千个线索拼凑起来解开这个历史之谜。

He is a key piece of a much bigger jigsaw puzzle because he was a double agent. 他是解开一个更大的谜团的关键，因为他是一个双料间谍。