单选题
A recent study in Tanzania found that when pregnant women took vitamins every day, fewer babies were born too small. Babies that weigh less than two and one-half kilograms at birth have a greater risk of dying. Those that survive are more likely to experience problems with their development. And experts say that as adults they have a higher risk of diseases including heart disease and diabetes. The World Health Organization (WHO) estimates that every year twenty million babies are born with low birth weight. Nine out of ten of them are born in developing countries.
The new study took place in Dares Salaam. 4,200 pregnant women received multivitamins. The pills contained all of the vitamins in the B group along with vitamins C and E. They also contained several times more iron and folate than the levels advised for women in developed nations. Pregnant women especially in poor countries may find it difficult to get enough vitamins and minerals from the foods in their diet.
The scientists compared the findings with results from a group of 4,000 women who did not receive the vitamins. A report by the scientists, from the United States and Tanzania, appeared in the New England Journal of Medicine . Wafaie Fawzi of the Harvard University School of Public Health led the study. None of the women in the study had HIV, the virus that causes AIDS. The scientists reported earlier that daily multivitamins were a low-cost way to reduce fetal deaths in pregnant women infected with HIV. The earlier work in Tanzania also found improvement in the mothers in their number of blood cells known as lmphocytes. Lymphocytes increase the body"s immunity against infection.
The new study in pregnant women who were not infected with the AIDS virus found that multivitamins reduced the risk of low birth weight. Just under eight percent of the babies born to women who took the multivitamins weighed less than 2,500 grams. The rate was almost nine and one-half percent in the group of women who received a placebo, an inactive pill, instead of the vitamins. But the vitamins did not do much to reduce the rates of babies being born too early or dying while still a fetus. Still, the researchers say multivitamins should be considered for all pregnant women in developing countries.

单选题 How many babies are born with low birth weight in the developed countries every year according to WHO?

单选题 A pill of multivitamins may contain all of the following substances EXCEPT ______.

单选题 Which of the following is NOT one of the effects of multivitamins mentioned in the passage?

单选题 What a role do lymphocytes play in the human body?

单选题 How many percent of babies were born with low birth weight to women who were not infected with the AIDS virus and took the multivitamins according to a new study?