——You have been invited to attend an opening ceremony this weekend,sir.——I can't _____this as I will have some more important things to do then.A.contribute to B.resign to C.submit to D.sacrifice to为什么?重点请讲B、C区别.

关于一个独立主格结构的句子If i had been invited to your birthday party,i would have bought a birthday gift for you.若我想把这句话写成独立主格结构 那么if引导的从句该如何改写?我是这么写的：Having been invi you have never been to American ,have you 作否定回答：No,—— —— —Late again Where_____?—Sorry,I____in the heavy traffic,or would have been here earlier.A.were you;have got stuckB.have you been;have got stuckC.were you;got stuckD.have you been;got stuck 求详解 、、翻译 Have you been to? How have you been? Have you been recently. you have been you can have been have you been sleeping? you have been Have you been tricked? where have you been studying?-I have been in a high school —— headmaster is a womenwhere have you been studying?-I have been in a high school — headmaster is a women用that还是whose —So far,how long _________ you _________China?—For one year.A.have ; come to B.have;been toC.have; been in D.have;gone to where you have been与where have you been区别 Have you been in there?写成Have you been there? where you have been与where have you been区别 —Have you ever been to Harbin?—No,I've ________ been here.A.everB.already C.neverD.yet I have always been you