为什么不用had served?His brother who served in the army for 8 years is no working for MIcrosoft.

为什么不用had served?His brother who served in the army for 8 years is no working for MIcrosoft. My father,who __ on the International Olympic Committee all his life,is retiring next month.A.served B.is serving C.had served D.has served Mr.Brown would rather that his son___in the Royal Air Force last year.A.served B.had served C.could serve D.had a chance to serve Is Lin Tao a solider?No,but 和（）in the army for three yearsA.has served B .had served C was serving D served为什么C不对 Sam Benton, the local butcher, had lost his wallet while taking his savings to the post-office.为什么taking his savings为什么不用was taking his savings Is this the man that you served 为什么用that为什么用that 不用which? His sister left home in 1998,and has not been heard of since.请问：AND后为什么不用“had”? I __ he had finished his homework at this timeA.think B.thought这里为什么不用think呢? 新概念3册36his unit was lost and all records of him had been destroyed.lost为什么不用过去完成时 He－－－the chair before his brother returned为什么这里填had mended 不用has mended? he would have finished his college education,but he had to quit and find a job to support family句中为什么用had不用would have 直到看见妈妈,这个小孩才停止了哭泣.The little child din't stop crying until he had seen his mother.为什么用had seen,不用saw? 英语翻译had为什么不用will have? He did not have a good reputation in his home town.这里为什么用have而不用had?过去式的话应该是要用had啊.那had应该在什么情况下使用? simon thought his computer was broken until his little brother pointed out that he had forgotten主句为什么不用过去完成时,因为simon thought这个动作发生在his little brother pointed out 之前 He drove home as quickly as he could only to find his house (had been destoryed) in the fire为什么不用was being destoryed?再说明白点 The young man accepted the publishment without protest because he thought it was his own fault.为什么这里用accepted而不用had accepted? That day he told his father （what） he had waited to hear .这句话括号中为什么用what不用that?