B
新素材 科普知识 Do you have memories from when you were a baby? Most of us don't have them. This is called "childhood amnesia(童年失忆症)". However，these memories are actually kept in the brain until we become adults，even though we aren't aware of them.
Professor Cristina Alberini at New York University found that the experiences in infancy(婴幼儿期) are kept as hidden memories. It happens in the hippocampus when an infant's(婴儿的) brain is growing. Changes in brain chemicals help this process. Alberini did experiments on mice and found that adding some chemicals later can bring back hidden memories. This shows that early memories aren't lost but are kept. "If the children are learning difficult situations in early childhood，their brains are going to be shaped based on that experience，" Alberini said. Her study shows these hidden memories may influence people's learning abilities throughout their lives and lead to some mental(精神的) health illnesses.
Although most of us can't remember the things that happened to us when we were little，the age at which each person has their first memory can be different.
Different backgrounds may explain the difference. Professor Wang Qi at Cornell University in the USA has shown that the earliest memories of Americans date back to around 3.5 years of age，almost six months earlier than in Chinese people. Wang said that this is because American people are more self-focused(以自我为中心的). However，in Asia，people play more roles in society and have more relationships with others. So it may take more time for Asian babies to remember many details.
How often parents talk about past experiences with their children can also influence when first memories appear. New Zealand's Maori people have their first memories as early as at the age of 2.5. It's because the Maori culture values stories and deep conversations about past events. Conversations are the key to keeping memories when kids can form mental images of the things that happened to them.
()29. According to the passage，"childhood amnesia" refers to "".
A. inability to recall early childhood experiences
B. difficulty children have forming(形成) memories
C. worry about the truth of early memories
D. loss of memory abilities in the childhood
()30. According to the passage，the underlined word "hippocampus" is probably .
A. a name of a scientific experiment
B. a part of human brain
C. a kind of special medicine
D. a kind of chemicals
()31. According to the passage， people are the ones who form first memories earliest.
A. Chinese
B. American
C. European
D. Maori
()32. On which website can we probably read the above passage?
A. www.crossculture.com
B. www.mentalhealth.com
C. www.brainandmemory.com
D. www.scienceandtech.com