第4部分：阅读理解（第31〜45题，每题3分，共45分）

　　第二篇 Dangers Await Babies with Altitude

 　　Women who live in the world’s highest communities tend to give birth to under-weight babies, a new study suggests. These babies may grow into adults with a high risk of heart disease and strokes.

　　Research has hinted that newborns in mountain communities are lighter than average. But it wasn’t clear whether this is due to reduced oxygen levels at high altitude or because their mothers are undernourished —many people who live at high altitudes are relatively poor compared with those living lower down.

　　To find out more，Dino Giussani and his team at Cambridge University studied the records of 400 births in Bolivia during 1997 and 1998. The babies were bom in both rich and poor areas of two cities: La Paz and Santa Cruz. La Paz is the highest city in the world, at 3.65 kilometers above sea level, while Santa Cruz is much lower, at 0.44 kilometers.

　　Sure enough, Giussani found that the average birth weight of babies in La Paz was significantly lower than in Santa Cruz. This was true in both high and low-income families. Even babies bom to poor families in Santa Cruz were heavier on average than babies bom to wealthy families in lofty La Paz. “We were very surprised by this result，，，says Giussani.

　　The results suggest that babies bom at high altitude are deprived of oxygen before birth. “This may trigger the release or suppression of hormones that regulate growth of the unborn child, “says Giussani.

　　His team also found that high-altitude babies tended to have relatively larger heads compared with their bodies. This is probably because a fetus starved of oxygen will send oxygenated blood to the brain in preference to the rest of the body.

　　Giussani wants to find out if such babies have a higher risk of disease in later life. People bom in La Paz might be prone to heart trouble in adulthood, for example. Low birth weight is a risk factor for coronary heart disease. And newborns with a high ratio of head size to body weight are often predisposed to high blood pressure and strokes in later life.

　　32. What does the new study discover?

　　A. Babies bom to wealthy families are heavier

　　B. Women living at high altitudes tend to give birth to underweight babies

　　C. Newborns in cities are lighter than average

　　D. Low-altitude babies have a high risk of heart disease in later life

　　33. Giussan and his team are sure that

　　A. babies bom in La Paz are on average lighter than in Santa Cruz

　　B. people living in La Paz are poorer than those in Santa Cruz

　　C. the birth weight of babies bom to wealthy families is above average

　　D. mothers in La Paz are commonly under-nourished

　　34. It can be inferred from what Giussan says in Paragraph 4 that

　　A. he was very tired

　　B. the study took longer than expected

　　C. the finding was unexpected

　　D. he was surprised to find low-income families in La Paz

　　35. The results of the study indicate the reason for the birth of underweight babies is

　　A. lack of certain nutrition B reduction of oxygen levels

　　A. poverty of their mothers D  different family backgrounds

 　　40 t can be learnt from the last paragraph that

　　A. underweight babies have a shorter life span

　　B. babies bom to poor families lack certain hormones before birth.

　　C. high-altitude babies tend to have high blood pressure in their later life

　　D. newborns in wealthy families have larger heads compared with their bodies.
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