Singing security guards

Their job is to keep passengers on the Sao Paulo underground safe.

But, once a month, instead of patrolling巡邏 the platforms, nine security guards treat commuters上班族 to a concert. 

They use the stations as venues場地 and play an eclectic mix of samba, rock and opera. 

The band is so successful that more members of staff want to take their place in the spotlight聚光燈.
http://www.bbc.co.uk/worldservice/learningenglish/language/wordsinthenews/2012/11/121114_vwitn_singing_security_guards.shtml