My uncle has been to Beijing ( ).He will go there for a third time next year

问题描述:

My uncle has been to Beijing ( ).He will go there for a third time next year
括号里填什么单词?

填twice:两次
因为前后照应,后句说到;他明年将去北京第三次,那么前面很容易想到我的叔叔已经去过北京两次了.