新疆地区正式隶属中央政府管辖开始于[ ]

A．汉高祖时    

B．汉武帝时    

C．汉宣帝时    

D．汉光武帝时

- _________  have you been to New York?            

-Twice.[ ]

A. How often                  

B. How much time            

C. How many times              

D. How long