2. 外语
  3. Traditional plant breeding involves crossed varieties of the 【M1】______ same species in ways they could cross naturally. For exa

Traditional plant breeding involves crossed varieties of the 【M1】______ same species in ways they could cross naturally. For exa

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问题     Traditional plant breeding involves crossed varieties of the 【M1】______
same species in ways they could cross naturally. For example,
disease-resistant varieties of wheat have been crossed with
highly-yield wheat to combine these properties. This type of 【M2】______
natural gene exchange is safe and fairly unpredictable. 【M3】______
    Genetic engineering(GE)involves exchanging genes between
unrelated species that cannot naturally exchange genes with each
other. GE can involve the exchange of genes between vastly
different species, e. g. putting scorpion toxin genes into maize or
fish antifreeze genes into tomatoes. It is possible that a scorpion
toxin gene, even when it is in maize DNA, will still get the
organism to produce scorpion toxin — but what other effects may 【M4】______
have on this alien environment? We are already seeing this 【M5】______
problem — adding human growth hormone genes to pigs certainly
makes them grow — but it also gives them arthritis and makes them
cross-eyed, that was entirely unpredictable. 【M6】______
    It will be obvious, for example, that gene for human 【M7】______
intelligence will not have the same effect if inserted into cabbage as 【M8】______
it had in human DNA — but what side-effect would it have? In
other word, is GM(Genetically Modified)food safe to eat? The 【M9】______
answer is that nobody knows because long-term tests have not been
carried out.
    The current position of the UK Government is that "There is
no evidence of long-term dangers from GM food." In the US, the 【M10】______
American Food and Drug Administration is currently being
prosecuted for covering up research that suggested possible risks
from GM foods.
【M5】
选项
答案on—in
解析 介词错误。本处用on还是in将会带来两种完全不同的意思，用on则句子的意思是“将会对这完全陌生的环境带来怎样的影响”，而如果用in则是指“某种基因在这完全陌生的环境中将会出现怎样的影响”。从接下来的一句话可以看到，这里并不是指基因对环境的影响，而是对被植人动植物的影响，因此on不合适。
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