a few decades的用法和样例：
- This species will be extinct in a few decades.
- I had my own encounter with Dirac a few decades later.
- In a few decades, all varieties of cells have wormed their way into every nook.
- A few decades ago, a statement like this would have seemed unimaginable.
- A few decades ago, researchers discovered something surprising about the Eskimos living in Greenland.