Even better, Paley’s Remote Scanning Services Company could detect crop problems before they became visible to the eye. Mounted on a plane flown at 3,000 feet at night, an infrared scanner measured the heat sent out by crops. The data were transformed into a color－coded map showing where plants were running “fevers”. Farmers could then spot－spray, using 50 to 70 percent less pesticide that they otherwise would.

　　The bad news is that Paley’s company closed down in 1984, after only three years. Farmers resisted the new technology and long－term backers were hard to find. But with the renewed concern about pesticides on produce, and refinements(改进) in infrared scanning, Paley hopes to get back into operation. Agriculture experts have no doubt the technology works. “This technique can be used on 75 percent of agricultural land in the United States，” says George Oerther of Texas A & M, who recently retired from the Department of Agriculture, and he thinks remote infrared crop scanning could be adopted by the end of the decade, but only if Paley finds the financial backing which he failed to obtain 10 years ago.

　　28．In what situation will plants have a fever？(No more than 8 words)

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　　29．How can we apply pesticide spraying precisely？(No more than 10 words)

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