Everyone in our class was working hard and doing what we could _______ a good college.

He was really disappointed to find that he had failed to make himself ______, although he tried his best to describe vividly.

 The professor paused as if ___________ his students to ask questions on the point he had just made.

Many people spend half their time______ways of getting rich.

_______ from father to son, the music has not changed for centuries.