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问题 单项选择题

已经丧失生物活性的实验材料是（）

A.经盐酸解离后的根尖细胞

B.质壁分离又复原的细胞

C.能发生反射的脊蛙的心肌细胞

D.收集到试管内的唾液淀粉酶

答案

参考答案：A

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Fit at Any Size


Nikki Blonsky is exactly the role model most parents dream of for their kids. She’s happy, she’s successful, she’s overcome obstacles—no wonder her young fans adore her. She’s also overweight— by some measures very overweight—in a culture that fetishizes thin.
(41)Blonsky is such a lucky dog, because she wouldn’t have been a popular figure she had been born a decade earlier.
(42)Happiness might be the most difficult word to define, but at least people are increasingly aware of the fact that the body shape does not determine happiness.
(43)Nobody likes to be over-weighted, yet it’s not our right to make the decision.
(44)Before you let your kids to lose weight, you should make sure what they are losing, weight or health.
(45)I you only feel hungry, then you can freely enjoy the joy of eating and drinking; however, if you bear the word "weight" in your mind, you can’t do that.
Amid all this back-and-forth, however, there is one point that everyone agrees on: exercise definitely improves a child’s overall sense of well-being. Cooper, who invented aerobics a generation ago, has been testing the physical fitness of schoolchildren over the past decade and has consistently found that active kids do better academically, have fewer disciplinary issues and maintain better medical histories. "A child doesn’t need to be a star athlete or a tong-distance runner," Cooper says. "Even taking the stairs instead of an elevator has positive effects. "
[A] There’s little doubt that being obese puts inactive youngsters at a higher risk for several health conditions, including Type 2 diabetes, high blood pressure and heart disease. But almost no studies have been done evaluating the pros and cons of kids being fat yet active. Plus, reports on adults in similar situations have conflicted. Since the 1970s, doctors at the nonprofit Cooper Institute in Dallas have gathered data from more than 100,000 patients who have been weighed, measured and made to run on treadmills while their vital signs are monitored. "We’ve long concluded that people who are overweight and active can be healthier than those who are thin but sedentary", says Dr. Kenneth Cooper, the institute’s director. "There’s no reason to believe that conclusion doesn’t apply to our children too. "
[B] Behind the push to get kids fit is the growing recognition that, in many cases, there’s just no fighting the natural rhythms or shape of a child’s body. Throughout childhood and adolescence, hormones may cause weight to fluctuate dramatically. Plus, nature determines whether we’re all going to be stocky, a beanpole or something in between before we’re even born. "Most body weights and types for children and adults are genetically determined", says Glenn Gaesser, a professor of exercise physiology at the University of Virginia. "There are a lot of kids who are just naturally heavier than their peers but may be even healthier. "
[C] Difficult as it is to hear that your child is overweight, placing a child on an enforced diet may do more long-term harm than good. Doctors have yet to find a weight-loss program that has proved universally effective and safe, especially for children. More often, dieters will lose weight in the short run only to regain it. Research suggests that the repeated losing-regaining cycle can lead to loss in bone density and lean muscle mass, organs and bones, jeopardizing overall health. In fact, at least 15 major studies have shown higher death rates for adults after repeated losing regaining weight cycling.
[D] Plus-size celebrities like Blonsky—or, for that matter, her Hairspray co-stars John Travolta (albeit in a latex fat suit) and Queen Latifah—are increasingly spreading the message that slim is not the last word in happy. Fit means happy too; so does staying active; so does loving your body no matter its shape. The key is to get that body healthy and keep it that way. The numbers on the scale—pediatricians, nutritionists and psychologists now argue—should start to come second to physical fitness as a gauge for health.
[E] As many as 10 million women and 1 million men in the U. S. suffer from an eating disorder, according to the National Eating Disorder Association (NEDA). Nearly 90% of those afflicted are under the age of 20, and females between the ages of 15 and 24 are 12 times as likely to die from anorexia as any one other cause of, death. A 2005 study published in the journal Pediatrics determined that of 10,000 teens surveyed, less than half of the males and about a third of the females were happy with their bodies. "Parents face a complicated situation", Tim Brownell, an expert from NEDA, says. "They have to promote healthy weight, but they also don’t want to change children into diet-crazed fanatics. "
[F] There was a time when that alone would have been enough to keep Blonsky, the 19-year-old star of the movie Hairspray, out of the fan magazines and off the posters decorating grade-schoolers’ bedroom walls. But that time may at last be ending. The national obesity epidemic did not happen in a vacuum. It occurred in an era in which fashion models have got thinner and thinner, the tolerance for even a little flab has grown lower and lower, and the rates of eating disorders like anorexia have climbed higher and higher. In that environment, children and adolescents trying to develop a healthy body image have almost no chance at all.
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