Mrs. Obama introduced the Let’s Move _______ yesterday. Its goal is to reduce children obesity(肥胖) today and in the future.

A．challenge

B．battle

C．campaign

D．behavior

西斯蒙第的经济危机理论是一种（）

A.由供给不足引发的经济危机理论

B.由消费不足引发的经济危机理论

C.由信用破坏引发的经济危机理论

D.由农业衰败引发的经济危机理论