a passing fad的用法和样例：
- His interest in photography is only a passing fad.
- Will Tom continue to collect stamps or is it only a passing fad?
- Rap music proved to be more than just a passing fad.
- Currently, Pu'er Tea is very popular, but maybe it's just a passing fad.
- Choosing to become more than just a passing fad, Uma left for England.