GDP是指一个国家（或地区）所有（）在一定时期内生产活动的最终成果。

A．本国公民 

B．国内居民 

C．常住居 

D．不包括外国人的常住居民

—How well do you know the Opera House?

—I know the place very well. I _______ Sydney many times. [ ]

A. have been in

B. have been to

C. have gone to

D. have arrived in