- do you watch TV? ---Only once on Saturday evening. You know as a student I am too bus

问题补充：

--- do you watch TV?

---Only once on Saturday evening. You know as a student I am too busy.

A. How much

B. How long

C. How soon

D. How often

答案：

A. How much

B. How long

C. How soon

(答案→)D. How often

解析：How much多少钱；How long多长；How soon多久；How often多久一次。根据下文，只在周六晚上一次。可知上文提问频率，故选D。