We can do a lot to stay healthy. __________, we should eat a balanced(平衡的) diet.
——Who is knocking at the door? ——It ______ Mr. Black, because he_______Washington.
In winter people usually keep flowers in their houses to ___them from the cold.
—— I feel tired and sleepy. ——Why not _______?
The picture shows us _______ in Nanjing in the past.
―What colours can give you a happy and satisfied feeling? ―________.