has been to the zoo for five times 和My mom has been to Beijing twice.为什么一个要用for一个又不用?

分类: 作业答案 • 2021-12-19 16:28:13

问题描述：

has been to the zoo for five times 和My mom has been to Beijing twice.
为什么一个要用for一个又不用?

答

twice这个词本身就是adv.两次;两倍;兼
for+n.for two times=twice