The doctors have done ______ they could ______the child.

People living in the desert choose to keep their ancient lifestyles and customs, _______people in cities throw away their cultural traditions.

At school，some students are active ________ some are shy，yet they can be good friends with one another.                                                    

—It’s a pity that Wang Qiang failed in the driving test again.—How can you expect him to pass _______ he hasn’t been practicing enough?

______ a phone is of great help, I don’t think it’s a good idea to spend too much time on it.