The Chinese are looking forward to the first _______to land on the moon after three Chinese astronauts’ successful trip to space.      

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. 

. He is clever and has a____________for learning language. 

What is the ______ to Beijing and back?

Life is full of _______.School is thought as the most ­­­_______ obstacle(障碍) in the lives of youth today.