Shanghai and Nanjing are among the most importantcities in China _____ their size and population

I am _______ about what I say because careless remarks are likely to hurt others’ feelings.

All his free time is ______ by volunteer work, but he feels it meaningful.

I believe that human cloning is wrong. If we toy with nature, we will have to deal with the _______.

My teacher _____ me the key to the classroom but I’m afraid I _____ it