They have been here once.把been换成came怎么样

they have been here since 1988,对1988进行提问,（）（）have they been here? They have been here once.把been换成came怎么样 they have been here since 2000____ ____ ____they been here? They have been here for two days.(改为同义句)They _____ here two days _____. They have been here since 2000.划since 2000.（对划线提问）____ ____have they been here? they have been away from here since two years ago同义句 ___ ___ two years ___ they left here they have been living here for four and a half years同义句they have been living here for ___ ___ ____ ___ ____. Where have they been? They ____ here for more than a month.A.have arrived B.have reached C.have come D.have been 改错:Someone have been here It's about three years since they＿here.是填came还是have been? since,they,been,from,ago,two,here,away,have连词成句 They have been here since 2000 （对划线提问）线在2000下,求回答, if they had starded earlier than expect,they would be here nowwould be 为什么不能换成would have been they have gone to that mall many times since they moved here 为什么用 gone to ,不用been to You have been here,的have They have a____ been there They must have been here the day before yesterday,__________?A.mustn't they B.didn't they C.mustn't have they D.had they 为什么有yesterday 就要用didn't they?A.为什么不可以呢?