请解释过去完成进行时和过去完成时在这个句子中的区别
问题描述：
请解释过去完成进行时和过去完成时在这个句子中的区别
They ____________ (work) on the program for almost one week before I joined them,and now we ____________ (still work) on it as no good results have come out so far.had been working
答
They ____________ (work) on the program for almost one week before I joined them答案：had been working或had worked用完成进行时 强调动作已经不间断地一直进行 了 一段时间用完成时 强调动作开始的状态已经 ...