— do I have to change the robot’s batteries? —Every two months.
A. How long
B. How soon
C. How often
D. How many
网友回答
A. How long
B. How soon
(答案→)C. How often
D. How many
解析：本题的回答语意思为每两个月，表示的是频率，对此提问应该用how often，故选C,how long对长度提问，how soon对多久以后提问，how many对可数名词数量提问。