has been to the zoo for five times 和My mom has been to Beijing tw_英语解答

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?

人气：291 ℃　时间：2019-09-17 04:26:57

解答

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