a detective agency的用法和样例：
- Although they are only janitors at a detective agency, the boys pass themselves off as sleuths and are engaged to guard an inventor delivering a new bomb.
- It would have cost Brown less to have forgotten the debt than to try to trace the couple through a detective agency,but he hated being diddled and swore to have his pound of flesh.
- The tramp was none other than a detective in disguise.
- The company hired a detective to investigate the accident.
- He have a good track record as a detective.