问题 选择题

下列说法不正确的是 [ ]

A.氮气、乙炔、二氧化碳分子中均含有2个π键

B.乙烯分子中p-pπ键的电子云位于由碳氢原子核构成的平面的上下

C.N2、O2、F2的键能依次增大,单质活泼性依次增强

D.HF、HCl、HBr、HI分子中的键长依次增大,稳定性依次减弱

答案

答案:C

材料分析题
阅读理解

C

Organic food has no nutritional or health benefits over ordinary food,according to a major study.

Researchers from the London School of Hygiene & Tropical Medicine said consumers were paying higher prices for organic food because of its imagined health benefits,creating a global organic market worth an estimated $48 billion in 2007.

A systematic review of 162 scientific papers published in the scientific literature over the last 50 years,however,found there was no significant difference.

“A small number of differences in nutrient content were found to exist between organically and conventionally(通常)produced foodstuffs,but these have nothing to do with public health,” said Alan Dangour ,one of the report's authors.

“Our review indicates that there is currently no evidence to support the selection of organically over conventionally produced foods on the basis of nutritional superiority .”

The results of research,which was commissioned by the British government’s Food Standards Agency,were published in the American Journal of Clinical Nutrition.

Sales of organic food have fallen in some markets,including Britain,as a slowdown in economic growth has led consumers to cut back on purchases.

The Soil Association said that growth in sales of organic products in Britain slowed to just 1.7percent,well below the average annual growth rate of 26 percent over the last decade.

64. Why does organic food cost more than conventionally produced food?

A. Because people think they are much healthier.    B. Because they are more delicious.

C. Because people prefer organic food.            D. Because they sell better.

65. According to the study,organic food is_________ than conventionally produced food.

A. much healthier           B. better       C. no healthier           D. less healthier

66. Sales of organic food have fallen because of___________.

A. high price            B. economic decline       C. bad service           D. poor quality

67. Where can you find this passage in a newspaper?

A. Economy            B. Science.      C. Food & Nutrition      D. Fashion