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Which of the following is TRUE according to the text？
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The traditional ways of increasing the yields of chemical do NOT include ______.
Researchers have long known that stressing plants can force them to take defensive action, often ramping up the production of protective chemicals that, for example, make them more resistant to insect attack. It has become common practice to stress such plants into increasing their yields. This is usually clone using physical stress elicitors (诱导子), including bits of the micro-organisms that normally attack the plants, or irritants made from metallic compounds such as copper chloride. These are effective, but they come at a cost. Most elicitors are toxic to plants and can build up in tissues, making it necessary to occasionally "clean" a plant of the chemicals so they keep having the same effect.
Recently, research groups at the University of Arizona in Tucson found that the application of an electric current to the hairy roots of the poisonous herb Hyoscyamus muticus stimulated the production of the herb's toxin hyoscyamine (天仙子胺). This unpublished finding inspired Hans Van Etten, also of the University of Arizona, and his colleagues to test sub-lethal levels of electrical currents on other plants, to assess electricity's potential to elevate chemical production.
The researchers exposed eight different plant species (ranging from Japanese pagoda tree seedlings to pea plants) to weak electrical currents of 30 milliamps. Seven of the plants increased their production o{ defensive chemicals. The average boost of chemical production was 20 times, they report in Biotechnology Progress. One plant, a type of alfalfa, increased its chemical yield by 168 times. These values are very similar to those achieved using chemical elicitors, and seem to have no lethal effects-just a negative effect on growth. The treatment can be used over and over again without the build-up of any unwanted material.
The useful compounds would be very easy to harvest: they simply pour out into solution if the plants are grown hydroponically. "The fact that we can use electricity instead of toxic materials to elicit chemical production is very exciting because it means we get to look at how these chemicals form. without having to constantly add and remove toxins from the system," says Van Etten. "This is a really novel and creative approach that I've never seen before," says plant metabolic engineer Fabricio Medina Bolivar from Arkansas State University in Jonesboro. "The possibilities for using electricity with plants in this way are absolutely tremendous. "
Electricity acting on plants can be used to ______.
Which of the following statements is TRUE？
听力原文： Gates was born and brought up in Seattle. At the age of 14, he founded a computer programming company with three friends, and they had earned ＄ 20,000 by selling their traffic-counting system to local governments. In 1975, he dropped out of his law course at Harvard to found the Microsoft Software Company in Washington. Gates' domination of the emerging computer industry began in 1980-1981, when he devised an operating system and licensed it to IBM. MS-DOS became the standard operating system for nearly all IBM personal computers. During the 1980s, Microsoft also developed more specialized software. When the company went public in 1986, Gates became a multimillionaire at the age of 31. Five years later, he was ranked as the world's richest man. In the 1990s, Gates made a fresh fortune from sales of windows, a system that enables a computer to be operated with on-screen symbols rather than complex keyboard commands. A revised was launched amid huge publicity in 1995.
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