---do you visit your uncle?---once a week .A. How longB. How manyC. How muchD. How often

问题补充：

---do you visit your uncle?

---once a week .

A. How long

B. How many

C. How much

D. How often

答案：

A. How long

B. How many

C. How much

(答案→)D. How often

解析：how long多长、多久 ； how many 多少（对可数名词多少进行提问）；how much多少（对不可数名词进行提问）；howoften意为“多久……次、是否经常”,用来提问在某一特定的时间进行某个动作的次数,答语通常是always,usually,often,sometimes,once/twice a day.本句答语是once a week一周一次，所以答案是D。