(They must have been there yesterday ,______they?)能用"weren't they" 还是"didn't they"?

They are wet all over.They _____ the rainA must have been caught inB must have been caught by (They must have been there yesterday ,______they?)能用weren't they 还是didn't they? It must have been they who picked the flowers.这里的强调句的must have been 为什么用现在完成时? must have been done must have done must have/ must have been的区别 It must have been they who gave the signal.为什么是they而不是them呢? I think they were Canadian.I don't think they were.They can't have been Canadian.They must have been Australian.帮我看看有无语法错误 Where have they been? she must have been forty.变反意疑问句!They must have seen the film.反意疑问句The old man must have been a Swedish.否定句My father must have gone to work.反意 They must have been to the USA,have not they?与He must have been to the USA,was not he?区别最好讲讲为什么句子主语一换,must反义疑问句就不一样了? 一道英语选择,These trees must have been planted three years ago,____?A weren't they B must't theyC didn't they D haven't they you must consider how dependent on regular rainfall they must have been.后面have been中been!you must consider how dependent on regular rainfall they must have been.句意是一必考虑他们当时如此的依赖常规的降雨!其句中have been Most students felt disappointed at the party.They said that it ___better organizedA.had been B.could have been C,must have been D.would be must not have been;could not have must have been与must have done的区别? many families who don't meet need eligibility have been willing to pay whether they must for a big-name school.中they must for 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?