had been doing 和had been done有什么差别
题目
had been doing 和had been done有什么差别
答案
1、首先要区分has been done与 had been done的区别：have/has been done 是现在完成时的被动语态.表示某事被做,.如：The problems have been solved.这些问题已经被解决了.had been done 则是过去的过去,是过去完成...
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我想写一篇关于奥巴马的演讲的文章,写哪一篇好呢?为什么好
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