a cautionary tale的用法和样例：
- A cautionary tale; cautionary advice.
- Japan is a cautionary tale for anyone with an eye for green shoots.
- Which is why a study, called Interphone, provides a cautionary tale.
- MySpace, which was bought by News Corp in 2005, offers a cautionary tale.
- By way of a cautionary tale, it's worth reading the ``Which is the largest species of crocodile?