The study you have been making ________ the ancient Chinese characters is an instructive job.
As I will be away for at least a year, I’d appreciate _____ from you now and then so that I can know how everyone is getting along.
The program was so exciting that the children kept their eyes _____ on the screen.
The thief fell to the ground, his left foot _____ and blood _____ down from his mouth.
The monument was built in honor of the explorer who was believed _____ the river.
You can’t imagine what great trouble they have _____ the problem _____.