В каких случаях можно заменять полную форму to be 3л, ед. ч (is) сокращенной ('s)?Спасибо.

Bob is still in his hotel.He is still busy.
Miss Benett is on my list.
Bill is in time.It is only nine.
Tom Lloyd is old.He is seventy-nine.
Ben Dent is in his shop.It is only open till seven.
Eve is in Ben's shop.
Tim Dobbs is idle.his life is empty.He's so silly!
Little Nelly is in bed.She is still il.