过去完成时是had+done为什么在什么情况下had都不用变.而现在完成时的助动词有have和has

过去完成时是had+done为什么在什么情况下had都不用变.而现在完成时的助动词有have和has i (had done) my homework,i went home 为什么用过去完成时 I won't go home until I(have done)the job.这里为什么用have done不是had done呢?过去完成时 had done 是过去完成时,have done是现在完成时,那have been和had been呢?be不是动词呀?急急急急 It was the first time that I had seen his film.这句话是定语从句还是强调句型?二者如何区分?the first time 在句中作什么成分?I had seen this film 为什么要用过去完成时? 现在完成时 过去完成时 怎样强调动词 是have/had done+动词原型吗强调句 例如：that does sound great. It had been many years since my wife and I had gone dancing it + 过去完成时 + since + 例句：it + 过去完成时 + since + 过去完成时为什么不是it + 过去完成时 + since + 过去式?真的是it + 过去完成时 + since + 过去 he was told by a smiling policeman that his bicycle had been found 中的had been found用了什么语法?如果是过去完成时 为什么要加been 用括号动词的正确形式填空What did he say that he _(do)答案是had done 或would do.请问这个间接引语为什么用过去完成时或者过去将来时而不能用过去式did啊? 英语 过去完成时 untilI did not understand the problem until he had explained it.过去完成时表示两个动作中较早的过去.这个句子中,明明是先不懂、再解释,为什么had放在解释那边? 现在完成时和过去完成时一般的意思是什么 have done和had done的意思如题 没有 would had done 这种时态是吗?只有would have done.没有 过去将来过去完成时? We had some shoes like those a month ago,这是过去完成时吗?had done呀 这里没有过去分词啊. 过去完成时的构成过去完成时是由“had +动词的过去分词”构成,但是为什么说had通常用于任何人称?had到底怎么变化? By now I had forgotten about the pie and listened to grandma,mesmerized 为什么BY NOW 后的是过去完成时?mesmerized 在这里是作动词过去式还是形容词 应该翻译成什么意思·· was done是什么时态?was是过去式,have done是过去完成时,那么was done是什么时态. had looked这类短语是过去完成时么? 关于英语中直接引语和间接引语之间转换的问题直接引语是一般过去时,变间接引语改成过去完成时（did变had done）,直接引语是现在完成时,变间接引语时也改成过去完成时（have done变had done）