When ______, the problem of unemployment will arise.

A．Because they have signed a very important contract.
B．Because they will leave early tomorrow.
C．Because they have got a good night’s sleep.
D．Because they have received good service from the hotel.

A．He succeeded in beating a mugger in a fight.
B．He became a karate(空手道)expert.
C．He passed away in a hospital after a fight with a mugger.
D．He called the police after being mugged.