have left是什么時態

　　The new laws have left us little room to manoeuvre.

　　新法律沒給我們留下多少回旋的余地。

　　I seem to have left my book at home.

　　我大概是把書忘在家里了。

　　Years of fighting have left the area in ruins.

　　經年的戰事已經使得這個地區滿目瘡痍。

　　How many tickets do you have left?

　　剩下的票你還有多少張？

　　By the time this gets into print, they'll already have left the country.

　　這篇東西發表的時候，他們將已經離開這個國家了。