Teachers _______ be sensitive to the development level of each student so as to help them better.
The rescue worker looks very young but _______ she is more than thirty years old.
While _______ out of the window, I saw my father walking the dog in the garden.
Our monitor always comes to our help when we get into trouble _______ she is very busy.
Can you tell me when the plane _______ to Hong Kong this evening?
As neither of the two nations would _______, no agreement was reached that day.