do you do some outdoor activities?--Once a week.A. How longB. How muchC. How farD. How

问题补充：

-- do you do some outdoor activities?

--Once a week.

A. How long

B. How much

C. How far

D. How often

答案：

A. How long

B. How much

C. How far

(答案→)D. How often

解析：句意:-你多久做一次室外活动？-一周一次。how long 多长时间，针对一段时间提问；how much 多少，多少钱；how far 多远，提问距离；how often 多久一次，提问频率。根据这个对话中的回答once a week可知，这里说的是做事的频率。故选D。