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.
【M1】
选项
答案Crossed—crossing
解析 词汇错误。本句的意思是传统的植物种植包括将相同种类的不同变体相互交叉，involve后应该跟doing some—thing即要做某事而非“交叉后的不同种类”。实际上，从第二段的第一句话也可以看到类似的结构。
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