After her son died in a car accident, the old lady would sit at the window, ______ out and _______ in thought.    

Unless ________ to speak, you should remain silent at the conference.

________ not to miss the flight at 15：20，the manager set out for the airport in a hurry.　　　　　　　　　　　　　　　　　　　

He attended the party without _______________.

It’s a pleasure to watch the face of a _____ baby.