我刚刚收到弟弟蒂姆的来信i have just received a letter from my brother,ti

i have just received a letter from my brother,tim.这句为现在完成时.现在完成时强调的是这个动作过去开始到现在已经结束,并且对现在的影响.i had just received a letter from my brother,tim.这句为过去完成时,它强调的是这个动作在过去的某个时间点之前已经发生了.在第二句中没有过去的时间点,也没有两个先后的动作,所以不能用.
另外,在平时造简单句时尽量少用过去完成时,它一般用在主从句上.