2. 外语
  3. In recent years a new farming revolution has begun, one that involves the 【21】______ of life at a fundamental level — the gen

In recent years a new farming revolution has begun, one that involves the 【21】______ of life at a fundamental level — the gen

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问题      In recent years a new farming revolution has begun, one that involves the  【21】______   of life at a fundamental level — the gene. The study of genetics has  【22】______   a new industry called biotechnology. As the name suggests, it  【23】______   biology and modem technology through such techniques as genetic engineering. Some of the new biotech companies specialize  【24】______   agriculture and are working feverishly to duplicate seeds that give a high yield, that  【25】______   diseases, drought and frost, and that reduce the need for  【26】______   chemicals.  【27】______    such goals could be achieved, it would be most beneficial. But some have raised concerns about genetically engineered crops.
   In nature, genetic diversity is created within certain space. A rose  【28】______   be crossed with a different kind of rose, but a rose will never cross with a potato. Genetic engineering,  【29】______   , usually involves taking genes from one species and inserting them into  【30】______   in an attempt to transfer a desired characteristic. This could mean,  【31】______   , selecting a gene which leads to the production of a chemical with anti-freeze quality from an arc- tic fish, and inserting  【32】______   into a potato or strawberry to make it frost-resistant. In essence, then, biotechnology allows humans to  【33】______   the genetic walls that separate species.
     Like the green revolution,  【34】______   some call the gene revolution contributes to the problem of genetic uniformity — some say even more so that geneticists can employ techniques  【35】______   as cloning and  【36】______   culture, processes that produce perfectly  【37】______   copies. Concerns about the erosion of biodiversity, therefore,  【38】______   . Genetically altered plants, however, raise new issues, such as the effects that they may have  【39】______   us and the environment. "We are flying blindly into a new era of agricultural biotechnology with high hopes, few constraints, and  【40】______   idea of the potential outcomes," said science writer Jeremy Rifkin.  
【28】
选项 A、may
B、need
C、can
D、must
答案C
解析 may表示可能性，need表示“需要，有必要”，must表示“必须”，can表示“能够”。由常识可知，同一物种是能够进行杂交的，因此选can最恰当。
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