My father flies to Shanghai twice a month.对twice a month提问,_ _ your father fly to Shanghai?我总觉得少了条横线.
问题描述：
My father flies to Shanghai twice a month.对twice a month提问,_ _ your father fly to Shanghai?
我总觉得少了条横线.
答
你是对的,这里应该填三个单词：How often does your father fly to Shanghai?