一简谐运动的曲线如图11-2所示，则该振动的周期为（    )

图11-2

A．10 s

B．11 s

C．12 s

D．13 s

. Although Miss Black began her _______ by singing in a local pop group, she is now a famous singer in the world.

A．employment

B．career

C．occupation

D．profession