糖酵解时丙酮酸不会堆积的原因是
A. 乳酸脱氢酶活性强
B. 丙酮酸可氧化脱羧生成乙酰CoA
C. NADH/NAD+比例太低
D. 乳酸脱氢酶对丙酮酸的Km值很高
E. 丙酮酸作为3-磷酸甘油醛脱氢反应中生成的NADH的氢的接受者
3. The sentence “The genetic genie is out of the bottle.” in Para. 2 probably means _______ .
A. the genetic genie, the key technology in producing genetically modified foods, is out in the market
B. the genetic technology has come out of laboratories into markets
C. genetically modified foods are available everywhere
D. technology with which to produce genetically modified foods may have powers unpredictable or uncontrollable by man
4. According to the passage, biotech can help solve the problem by _______ .
A. producing foods that contain more nutrients needed by human beings
B. creating more varieties of foods
C. producing beta-carotene and vitamin A more efficiently
D. producing anti-virus crops
2. According to the passage, genetically modified foods ______ .
A. are superior to naturally grown foods
B. might prove to be risky to human health
C. are going to replace naturally grown foods
D. can solve the food problems in developing countries
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