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  3. For the past 10, 000 years humans have influenced the plants they use at first unknowingly, later by design. Today’s crops have

For the past 10, 000 years humans have influenced the plants they use at first unknowingly, later by design. Today’s crops have

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问题     For the past 10, 000 years humans have influenced the plants they use at first unknowingly, later by design. Today’s crops have been created by a process of selection and classical breeding. More specific improvements in breeding will be possible in future.
    Science has cracked the genetic information code. Green gene technology is an effective tool in crop breeding, enabling us to develop new crops even more rapidly and specifically.【F1】We can make them more efficient, optimizing their contents and valuable substances to suit the wishes and requirements of customers and the processing industry. Their metabolism can be individually modified, making them produce starch, protein and fats with special properties. Through gene transfer plants can be made more resistant to viruses, bacteria, harmful fungi and insect pests.
    【F2】Genetically modified plants can be cultivated to possess improved stress behavior, with the result that they absorb water better in dry locations and can make more efficient use of soil nutrients. We can also optimize weed control. To do so, we make crops tolerant to environmentally sound and easily degradable herbicides. This is not as simple as it sounds. But we have been successful: Innovator has been on the Canadian market since 1995. This is the first oilseed rape variety to contain the glufosinate tolerance gene, facilitating the use of AgrEvo’ s broad-spectrum herbicide liberty.
    We are committed to green gene technology, with which we aim to make crop breeding even more efficient and environmentally friendly.【F3】Before being brought on to the market these genetically modified plants are researched and tested for years until the questions posed regarding their safety have been answered.【F4】This is a great opportunity for us to realize our vision: the use of faster methods to breed varieties which will continue to provide us with sufficient food and raw materials in future. Our fossil reserves will soon be exhausted. Experts estimate that we only have e-nough oil for another 43 years and natural gas for less than 60.
    【F5】This means we must rethink and act accordingly, using new crop varieties to step up the move to reusable sources of raw materials and energy. In other words, green gene technology is the key technology for sustainable agriculture.
【F3】
选项
答案经基因改良的作物，要经过数年的研究实验，澄清了安全性问题后，才投放市场。
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