is加過去分詞是什麼時態

Eight hours on a bus is no joke, is it.

坐８個小時的公交車可不是鬧着玩兒的，對吧。

He is in no doubt as to what is needed.

他對需要些什麼心中有數。

It is a country where corruption is rife.

這是個腐敗成風的國家。