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  3. One of medicine’s fundamental beliefs about pregnancy and the development of the human fetus has been challenged. Until recently

One of medicine’s fundamental beliefs about pregnancy and the development of the human fetus has been challenged. Until recently

admin2010-01-15  50
问题      One of medicine’s fundamental beliefs about pregnancy and the development of the human fetus has been challenged. Until recently, it was thought that the fetus was a parasite capable of extracting all the nutrients it needed from the mother. It is now realized that adequate nutrition during the entire course of the pregnancy is necessary for proper fetal development.
     In early pregnancy, certain changes occur in the mother’s gastrointestinal tract, resulting in more efficient absorption of specific nutrients, such as iron and calcium. Furthermore, the maternal blood supply increases, so that nutrients can be transported via the uterine and placental blood systems: If the mother is undernourished, this "lifeline" to the fetus will be inadequately developed. Finally, fat is accumulated within the body to store the energy necessary for lactation (milk production), This preparation for lactation is so important that if the mother is inadequately nourished, it will take place even at the expense of fetal growth. It is a logical developmental occurrence, since in the natural world, no infant can survive without successful breastfeeding, and thus fetal growth is less of a priority.
According to the passage, what traditional belief has been questioned?
选项 A、The fetus grows at the expense of the mother.
B、Good nutrition is necessary throughout pregnancy.
C、The most important changes occur in early pregnancy.
D、The mother’s nourishment is more important than the baby’s.
答案A
解析 由题干可知，本题的答案应在文章的开头。第一段第二句中的“Until recently”和一般过去时的使用表明，该句表达的内容正是过去传统的观点，即“the fetus was a parasite capable of extracting all the nutrients it needed from the mother”。就是说The fetus lives on the mother and gets its nutrients from the mother。A项中的“at the expen
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