考博考试

【单选题】Caffeinated coffee may have an undeserved bad rap.
A、new study shows the decaffeinated variety may have harmful heart effects. The study showed that people who drank decaf had higher levels of a protein linked to heart disease risk compared with those who drank caffeinated coffee or no coffee. "But the differences were fairly small and there’s probably no health threat from drinking a cup or two of any type of coffee a day," says researcher H. Robert Superko, MD、The research is the latest entry into a long line of scientific studies looking at whether coffee drinking can lead to heart disease.
The participants were given premeasured bags of coffee to make in their coffee machines provided by researchers, They agreed to drink it black--no cream or sugar al-loweD、And they agreed to periodic blood tests so the researchers could keep track of exactly how much caffeine they drank. The 187 volunteers were assigned to one of three groups: no coffee, three to six cups a day of caffeinated coffee, or three to six cups of decaf.After three months, levels of apolipoprotein
B、ApoB、were up significantly in the decaffeinated group while staying relatively unchanged in the other two groups. The amount ofApo
B、has been suggested in other studies to be a better predictor of cardio-vascular disease risk.
There was one group for whom decaf appeared to be heart healthy: the overweight. For those who had body mass indexesBMIs) of more than 25, drinking decaffeinated coffee boosted levels of HDL (high density lipoprotein) by about 50%.Among those with lowerBMIs (who were not overweight), HDL dropped 30%.Elevated HDL is known to protect the heart.
Here’s also good news for people who love coffee:Drinking it doesn’t seem to cause long-term high blood pressure, a study suggests.Caffeine is a well-known ingredient in both beverages, and has been shown to cause short-term increases in blood pressure. Previous data on coffee and hypertension is mixeD、There’s a common perception that its temporary effects on blood pressure mean an increased long-term risk, saidDr. Wolfgang Winkelmayer, the study’s lead author. "We found strong evidence to refute that belief," the researchers wrote. There was even some evidence that people who drank lots of coffee--four or more daily cups of regular or decal--faced a slightly lower risk for developing high blood pressure than those who drank little or none. Winkelmayer said that might be because coffee has lots of antioxidants, substances that are thought to be helpful.
In the opening paragraph, the author introduces his topic by ______ .
A、posing an example

B、justifying an assumption
C．making a comparison
D．explaining a phenomenon

网考网参考答案：C
网考网解析：
第1段中，作者先说明一个问题，那就是Caffeinated coffee may have an undeserved bad rap。接着在下面将Caffeinated coffee与decaffeinated coffee做了比较，文中第3行也用了compared with those who drank caffeinated coffee，因此我们可以直接判断出作者的写作方法是做比较。故C正确。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>