His sister left home in 1998,and-----since.A has not been heard of B has not hear of 不知道为什么选A,运用的什么英语语法,

His sister went ____ once his mother left home.（用介词或副词） He left his sister alone at home.和He left his sister at home alone.有何区别?都对?还是就一个对 his sister didn't know the timebecause she _________her watch at home .a.leave b.left c.forght d.forgot His sister left home in 1998,and has not been heard of since.请问：AND后为什么不用“had”? 选择His sister left home in 1998,and ____since.A has not been heard of B has not heard of His mother looks after his sister at home（ ）（ ）after his sister at home? John left his car at home 英语语法的一个简单问题his sister left home in 1998,and has not been heard of since.为什么要加been?不加不行么? His sister left home in 1998,and ＿ since.A.had not been heard of B.has not been heard of C.ha his sister left home in 1998,and _____ since.为什么用has not been heard of 而不是has not heard of His sister left home in 1998,and-----since.A has not been heard of B has not hear of 不知道为什么选A,运用的什么英语语法, His mother looks after his sister at home怎么提问 His sister usually reads books at home (对画线部分提问) （）（） his sister usually () at home? 翻译Ted left his homework at home并回答 Tom left his home thirty years ago 同义句转换 his uncle left home when he was twenty同义句his uncle left home ______ _______ _______ _______twenty His sister left home in 1998,and__sinceA had not been heard ofB has not been heard of就是这两个选项搞不清楚,我觉得是选A啊,因为前面是过去式了啊,后面不就是过去完成时吗? His sister left home in 1998,and_______ ever since.A.had not been heard of B.has not been heard of C.had not heard of D.has not heard of