sniff something/someone out
phrasal verb with sniff verb uk/snɪf/ us/snɪf/
mainly US (UK usually smell something/someone out)
闻出，嗅出
to discover where something or someone is by smelling
At customs, dogs are used to sniff out drugs in passengers' luggage. 在海关，狗被用来嗅查乘客行李中的毒品。