We had lived in this town long enough to know who was who. [=to know the names of the different people, what they did, etc.]我们在这个镇住了很长时间，对这里的人很熟悉。

I'm still learning who's who around the office.我还在熟悉办公室每个同事的情况。

The guest list reads like a who's who of the publishing industry.这份宾客名单读起来像是出版界的名人录。

The convention was attended by a who's who of the publishing industry.参加这次大会的是出版界的名人。