Giving up my job to go back to full-time education was a big __________, but now I know it was the best decision I ever made. 

—I have to ask a(n) _____ of you because the luggage is too heavy for me.—Oh, with pleasure.

The manager of the company told us that very little _________ was made of the waste material in the past.

The lion is considered the king of the forest as it is a（n）______of courage and power.

I listened to Dr. Johnson’s lecture about biology, but I failed to get its key ____.