Coal is the second major natural r found in large quantities in the United States.
The poor man had a very unhappy ______(童年).
Three thousand ______(听众) crowded the concert hall.
The young couple are always ______(争辩) with each other about money.
We should care for the young and ______(尊敬) the elderly.
The police ______(观察) a man in black entering the bank.