2. 职称英语
  3. Traditional plant breeding involves crossed varieties of the 【M1】______same

Traditional plant breeding involves crossed varieties of the 【M1】______same

游客2024-11-29  32
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. [br] 【M6】
选项
答案 that—which
解析 句法错误。很显然，此分句应当是一个非限制性定语从句修饰前面所提到的意外变化，that不可以被用来引导非限制性定语从句，此处只能用which。
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