新概念英语第一册69课中语法新概念英语第一册69课中therewerehundredsofpeoplethere.mywifeandiwereattherace.ourfriendsjulieandJackerethere,too.youcanseeusinthecrowd.wearestandingontheleft.thereeretwenty

　　新概念英语第一册69课中语法

　　新概念英语第一册69课中

　　therewerehundredsofpeoplethere.

　　mywifeandiwereattherace.

　　ourfriendsjulieandJackerethere,too.

　　youcanseeusinthecrowd.

　　wearestandingontheleft.

　　thereeretwentycarsintherace.

　　wearestandingontheleft.这一句上下文都是用过去时.为什么这一句用现在进行时.

　　thankyouforyourhelp

　　用现在进与用过去时有什么区别呢？