—do you go to a movie?— Once a week.A. How often B. How long C. How soon

问题补充：

—do you go to a movie?

— Once a week.

A. How often B. How long C. How soon

答案：

解析：句意：你多久去看一次电影？一个星期一次。How often 多久一次；. How long多久；How soon多久以后。根据答语once a week可知该选A。