.--- Hurry up. The bus is coming. --- Oh, no. We mustn’t cross the street_______the traffic lights are green.
In many factories computers have ___________ the work of thousands of workers.
Nowadays, scientists are working hard to find a best way of treating addictions __________ drugs.
My doctor recommended that I _______ more exercise.
As a teacher you should _________ your method to ______ the needs of slower students.
----The boss said we had only three days to finish the task. ----No problem. We have already _________ two thirds of it.