such words have never been heard before 为什么加been希望具体语法指点疑惑拜托

这样的事闻所未闻：such a thing has never been heard of before; Because I never have been there before. i have never been a boarder before? they have never been held before in this country 为什么用been 不用 改病句 I have never heard such things before. 速度! Never before have I heard of such things的翻译 i have never been abroad before 这个before是什么词性 I never there before.A.have;been to B.have;been C.have;gone You have never been before,so not to lose Addicted to love who have never before been jealous. I have never been to __ amusement park before. The twins have never been to England before