A、By smiling to please others when they need care. B、By repeating one behavior familiar to their mothers’. C、By changing the env

Not long ago, many people believed that babies only wanted food and to be kept warm and dry. Some people thought babies were not able to learn things until they were five or six months old. Yet doctors in the United States say babies begin learning on their first day of life. Research scientists note that babies are strongly influenced by their environment. They say a baby will smile if her mother does something the baby likes. A baby learns to get the best care possibly by smiling to please her mother or other caregivers. This is how babies learn to connect and communicate with other people. The American researchers say this ability to learn exists in a baby even before birth. They say newborn babies can recognize and understand sounds they heard while they were still developing inside their mothers. A new study in California says the first three years of a child’ s life is important for all later development. Experts from the study say mothers can strongly influence social development and language skills in their children in these three years.
Q:
19. What did people think of babies in the past?
20. How do babies learn to communicate with others?