do you have an English party?---Once a month A. How oldB. How farC. How oftenD. How lo

问题补充：

--- do you have an English party?

---Once a month

A. How old

B. How far

C. How often

D. How long

答案：

A. How old

B. How far

(答案→)C. How often

D. How long

解析：

根据 ---Once a month 可知横线处应该填一个表示问频率的词组，所以选C，句子意思为你多久参加一次英语派对。