happen 是不是瞬间动词

happen 是不是瞬间动词 know 是不是瞬间动词? know是不是瞬间动词? be 是不是瞬间动词呢? have been in是不是瞬间动词 .happen这个瞬间动词有完成时吗?It seems that no one knew what had happen happen是瞬间动词吧?为何还会有What was happening 这种用法呢? march是不是终止性（瞬间性）动词? happen 有没有进行时态?为什么教科书上有what was happening?瞬间动词有进行时态么? borrow,lend,return是不是都是瞬间动词?keep是延续动词吧? 瞬间动词改为持续性动词 英语动词 瞬间动词考查