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A. Baby rats.B. Animals.C. Old rats.D. Grown-up rats.Wh……

Motherhood may make women smarter and may help prevent dementia in old age by bathing the brain in protective hormones, US reseachers reported on Thursday.
Tests on rats show that those who raise two or more litters of pups do considerably better in tests of memory and skills than rats who have no babies, and their brains show changes that suggest they may be protected against diseases such as Alzheimer’s. University of Richmond psychology professor Craig Kinsley believes his findings will translate into humans.
"Our research shows that the hormones of pregnancy are protecting the brain, including estrogen, which we know has many neuroprotective effects," Kinsley said.
"It’s rat data but humans are mammals just like these animals are mammals," he added in a telephone interview. "They go through pregnancy and hormonal changes. "
Kinsley said he hoped public health officials and researchers will look to see if having had children protects a woman from Alzheimer’s and other forms of age-related brain decline.
"When people think about pregnancy, they think about what happens to babies and the mother from the neck down," said Kinsley, who presented his findings to the annual meeting of the Society of Neuroscience in Orlando, Florida.
"They do not realize that hormones are washing on the brain. If you look at female animals who have never gone through pregnancy, they act differently toward young. But if she goes through pregnancy, she will sacrifice her life for her infant—that is a great change in her behavior that showed in genetic alterations to the brain. \

What does the phrase "litters of pups" mean in the second paragraph()

A. Baby rats.
B. Animals.
C. Old rats.
D. Grown-up rats.

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单项选择题Sesame Street is actually ______. A. a street in the US B. a program for children C. a program for teachers D. a program for students

Although some educators object to certain elements in the program, parents praise it highly. Many teachers also consider it a great help, though some teachers find that problems arise when first graders who have learned from "Sesame Street" are in the same class with children who have not watched the program.
Tests have shown that children from all racial, geographical, and economic backgrounds have benefited from watching it. Those who watch it five times a week learn more than occasional viewers. In the US the program is shown at different hours during the week in order to increase the number of children who can watch it regularly.
The programs all use songs, stories, jokes, and pictures to give children a basic understanding of numbers, letters and human relationships. But there are some differences. For example, the Spanish program, produced in Mexico City, devotes more time to teaching whole words than to teaching separate letters.
Why has "Sesame Street" been so much more successful than other children’s shows Many reasons have been suggested. People mention the educational theories of its creators, the support by the government and private businesses, and the skillful use of a variety of TV tricks. Perhaps an equally important reason is that mothers watch it along with their children. This is partly because famous adult stars often appear on it. But the best reason for: the success of the program may be that it makes every child watching feel able to learn. The child finds himself learning, and he wants to learn more.