【请大家帮帮忙threemonthslater,thehostagesweremoredeadthanalive______________threemonthslater,thehostagesweremoredeadthanalive.A.HavingrescuedB.RescuingC.HavingbeenrescuedD.Rescued这道四选一我怎么选都是C,为什么】

　　请大家帮帮忙threemonthslater,thehostagesweremoredeadthanalive

　　______________threemonthslater,thehostagesweremoredeadthanalive.

　　A.HavingrescuedB.Rescuing

　　C.HavingbeenrescuedD.Rescued

　　这道四选一我怎么选都是C,为什么正确答案是D呢?有何语法依据?

　　10)_______,shanghaiisprobablythebestplaceforthenextAsianGames.

　　A.ConsideringallthingsB.Allthingsbeingconsidered

　　C.AllthingsconsideredD.Toconsiderallthings

　　请问这道题为什么是独立主格,为什么不能选择A选项?是怎么考虑出来的呢?