Because he doesn't know whom to talk with.

因为他不知道该和谁说话。

youdao

How can anyone know whom to trust?

怎能知道该去相信谁？

youdao

Dress and conduct yourself in a professional manner everywhere you go because you never know whom you'll meet.

时刻注重着装、言行的得体，因为你永远不会事先知道会遇到谁。

youdao

Second, the small group of voters -- all of whom know each other -- makes it impossible for an outsider to affect the voting in any way.

CNN: How secure is the papal election?

According to the Financial Times report, Janus Friis and our man Niklas Zennstrom -- whom you may know from a little company called Skype -- are supposedly developing a peer-to-peer IPTV service with the intention of distributing video online the same way Skype and its P2P approach distributed VoIP calling online.

ENGADGET: Skype founders to launch P2P IPTV for millions of people?

Her friends and her boyfriend joined the search on Tuesday along with coach loads of local people - many of whom did not know the missing woman - after a police appeal for help.

BBC: Dog teams to join search for missing Sian O'Callaghan