A short time before,great trees had covered the countryside for miles around.为什么用过去完成时a short time before 如果是过去的时间为什么不用过去时，而要用过去完成时

a short time before 和 a short time ago 的区别,可以举例说明, a short time ___(after,before,later,as sooon as) before that if I have time,I watch TV for a short time （） left before the meeting,it doesn't seem likely that will come.A in such a short time B only such a short time C with such a short time D without such a short time 什么用法? a short time =( ) not long before等于soon和in a short time和soon a short time ago中文 翻译：a short time ago ____ a short time,however,we will learn waht to do.A.Before B.After C.For D.In a love before time a love before time A short time before,great trees had covered the countryside for miles around.为什么用过去完成时a short time before 如果是过去的时间为什么不用过去时，而要用过去完成时 in a short time为什么time可数 翻译：His parents left mainland China for Hong Kong a short time before he was born.谢过~~~ New York became the capital of the USA for a short time (1789- 90) before Washington,D.C. with such a short timeleft before the deadline ,it doesn't seem likely that John will( )left,it doesn't seem likely that I will be able to finish the work before the deadlineA.having so short time B.having such a short time C.with short time D.with s ___left before the deadline,it doesn't seem likely that John will accomplish the job.A.Although such a short time B.It is ashort time C.With such a short time 求每个选项的解释 --------left before the meeting,it doesn't seem likely that they will come.A In such a short time B Only such a short time C with such a short time D without such a short time.为什么选C,其他的选项为什么是错的,