题目内容
Through using the brain is the best way to maintain good ______.
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Genetic engineering is absolutely good for human.
Anthropologists believe differences between traditional and modern societies are that in the old society ______.
Vitamin A is necessary for the body's natural defense system against disease. Vitamin A is needed to help prevent skin and other tissues from drying out. It also produces a light-sensitive substance in the eyes.
People who do not get enough Vitamin A cannot see well in the dark. They may develop a condition that dries the eyes. The condition can result in infections that lead to blindness.
A lack of Vitamin A is a major cause of blindness among children. Health experts estimate that 124 million children around the world do not eat enough foods with Vitamin A.
Vitamin A is found in fish liver oil and in the yellow part of eggs. Vegetables such as carrots and sweet potatoes contain beta carotene, a substance that the body changes into Vitamin A.
Public health campaigns to provide Vitamin A to those who need it have proved costly. And they are not always effective. That has led researchers to try to create foods with the vitamin.
Rice is one of the most common crops grown worldwide. However, normal rice lacks Vitamin A. Researchers at a laboratory in Switzerland found a way to change the genetic material of rice. They added three genes to the rice. The genes produce beta carotene, the chemical that our bodies change into Vitamin A.
The new rice has a golden yellow color. The researchers say 200 grams of the rice have enough beta carotene to provide the necessary amount of Vitamin A.
Biologist Mary Lou Guerinot of Dartmouth College wrote a commentary published with the report in science magazine. She said the rice is an excellent example of the good things that can be done with genetic engineering. However, critics of genetic engineering argue that changing plant genes could increase risks to human health or the environment.
With Vitamin A people won't get any diseases.
第一篇
It has been argued that an infant under three who is cared for outside the home may suffer because of the separation from his parents. The British psychoanalyst John Bowlby maintains that separation from the parents during the sensitive "attachment" period from birth to three may scar a child's personality and predispose to emotional problems in later life. Some people have drawn the conclusion from Bowlby's work that children should not be subjected to day care before the age of three because of the parental separation it entails, and many people do believe this. But there are also arguments against such a strong conclusion.
Firstly anthropologists point out that the secluded love affair between children and parents found in modern societies does not usually exist in traditional societies. For example, we saw earlier that among the Ngoni the father and mother of a child did not rear their infant alone--far from it. But traditional societies are so different from modern societies that comparisons based on just one factor are hard to interpret.
Secondly, common sense tells us that day care would not be so widespread today if parents, caretakers or pediatricians found that children had problems with it. But Bowlby's analysis raises the possibility that early day care has delayed effects. The possibility that such care might lead to, say, more mental illness or crime 15 or 20 years later can only be explored by the use of statistics. Statistical studies of this kind have not yet been carried out, and even if they were, the results would be certain to be complicated and controversial.
Thirdly, in the last decade, there have been a number of careful American studies of children in day care, and they have uniformly reported that day care had a neutral of slightly positive effect on children's development. But tests that have had to be used to measure this development are not widely enough accepted to settle the issue.
According to Bowlby, children under the age of three ______.
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