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简述间作的技术要点。

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油料作物的产量构成因素有哪些？

杠杆比率(1everage ratio)

某周的日均温分别为9°C ,9°C ,11°C ,12°C ,13°C, 15°C ,16°C，则对喜温作物(生物学零度为10°C)来说，这周的活动的积温为（）

A. 85°C
B. 67°C
C. 17°C
D. 18°C

In Bykovsky, a village of 457 on Russia&39;s northeast coast, the shoreline is collapsing, creeping closer and closer to houses and tanks of heating oil, at a rate of 15 to 18 feet a year.
"It is practically all ice - permafrost - and it is thawing." For the four million people who live north of the Arctic Circle, a changing climate presents new opportunities. But it also threatens their environment, their homes and, for those whose traditions rely on the ice-bound wilderness, the preservation of their culture.
A push to develop the North, quickened by the melting of the Arctic seas, carries its own rewards and dangers for people in the region. The discovery of vast petroleum fields in the Barents and Kara Seas has raised fears of catastrophic accidents as ships loaded with oil and, soon, liquefied gas churn through the fisheries off Scandinavia, headed to markets in Europe and North America. Land that was untouched could be tainted by pollution as generators, smokestacks and large vehicles sprout to support the growing energy industry.
Coastal erosion is a problem in Alaska as well, forcing the United States to prepare to relocate several Inuit villages at a projected cost of $100 million or more for each one.
Across the Arctic, indigenous tribes with traditions shaped by centuries of living in extremes of cold and ice are noticing changes in weather and wildlife. They are trying to adapt, but it can be confounding.
In Finnmark, Norway&39;s northernmost province, the Arctic landscape unfolds in late winter as an endless snowy plateau, silent but for the cries of the reindeer and the occasional whine of a snowmobile herding them.
A changing Arctic is felt there, too. "The reindeer are becoming unhappy," said Issat Eira, a 31-year-old reindeer herder.
Few countries rival Norway when it comes to protecting the environment and preserving indigenous customs. The state has lavished its oil wealth on the region, and Sami culture has enjoyed something of a renaissance.
And yet no amount of government support can convince Mr. Eira that his livelihood, intractably entwined with the reindeer, is not about to change. Like a Texas cattleman, he keeps the size of his herd secret. But he said warmer temperatures in fall and spring were melting the top layers of snow, which then refreeze as ice, making it harder for his reindeer to dig through to the lichen they eat.
"The people who are making the decisions, they are living in the south and they are living in towns," said Mr. Eira, sitting inside his home made of reindeer hides. "They don&39;t mark the change of weather. It is only people who live in nature and get resources from nature who mark it."
A push to develop the North, quickened by the melting of the Arctic seas, carries its own rewards and dangers for people in the region. The discovery of vast petroleum fields in the Barents and Kara Seas has raised fears of catastrophic accidents as ships loaded with oil and, soon, liquefied gas churn through the fisheries off Scandinavia, headed to markets in Europe and North America. Land that was untouched could be tainted by pollution as generators, smokestacks and large vehicles sprout to support the growing energy industry.