-- have you stayed in this school ?-For three years.A. How farB. How longC. How oftenD.

问题补充：

-- have you stayed in this school ?

---For three years.

A. How far

B. How long

C. How often

D. How many

答案：

A. How far

(答案→)B. How long

C. How often

D. How many

解析：B 根据答语“三年”得知，问的是“你在这个学校多久了？”，故选B。