英语语法的一些问题has been explained 和 had been explained 它们两个有什么区别吗?

英语语法的一些问题has been explained 和 had been explained 它们两个有什么区别吗? 初中英语语法has been和had been的区别 has been to has been in has been on 的区别 求初二上英语语法卷附答案 关于had has等英语语法has been V+ing和had been V+ing的区别. 一些关于英语语法的问题如图 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? has been open和has been opening有什么区别跟open有关的问题 一个简单的英语语法 there has been heavy rain in South China recently为什么用there has been 不用there was 一个关于英语语法的问题It signals a change in what has,until now,been a key element of scientific endeavor.这里的what引导的是个什么样的从句呢? 几个关于英语语法的小问题1.there's been a big mistake.为什么there's后面还要一个been? have/has been+pp和have/has+pp的区别是什么希望详细一些 3Q 关于现在完成时的一些问题.1.has been后跟动词的ING还是过去分词形式?2.在什么状态应用什么形式? 英语语法：He has been found guilty.请问guilty作句子什么成分?还能列举几个相似的句子吗? 一个简单的英语语法问题The boys___an apple 用have还是has 问个英语语法改错题His father has died for three years.为什么要把has died改成has been died?been有什么作用?现在完成时的构成里是have（has）+过去分词 没有been啊 为什么要加been?has 和been是算作助动词吗? will be和will的区别,has been away from和has away from比如这道题：A moment,please.I' m checking if Mr.Smith[ will be free ]tomorrow.为啥是will be不是will?还有been的用法,比如been on之类的Ex:Mark [has been away] from his hometo 关于现在完成时中has been和has gone的问题1.某人去某地,在某地去世,用has been还是has gone2.某人去某地,在某地去世,尸体被运了回来,用has been还是has gone 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,