1. (2020高二上·上海期末) 完形填空

Trackers on Ice

Just because a scientist puts a GPS tracking collar on a wild polar bear does not mean the animal will obligingly keep it on. 1, these huge collars are purposefully loose. If one becomes annoying, a bear can 2 it. But scientists have now found a way to use 3 from the discarded（丢弃的）devices.

"These dropped collars 4 would have been considered garbage data," says Natasha Klappstein, a polar bear researcher at the University of Alberta. She and her colleagues instead used 5 from such collars, left on sea ice in Canada's Hudson Bay, to track the ice itself. For their study, published in June in The Cryosphere, the researchers identified twenty collars that transmitted movement data in line with ice drift rather than polar bear 6 between 2005 and 2015. The resulting records of how melting ice typically drifts in Hudson Bay are unique. There are no easily 7 on-the-ground sensors, and satellite observations often cannot accurately capture the motion of small ice sheets.

The team 8 the discarded collars' movements with widely used ice-drift modeling data from the U. S. National Snow and Ice Data Center（NSIDC）. Collar data indicated that the NSIDC model underestimates the speed at which ice moves around in Hudson Bay-as well as the overall 9 of drift. Over the course of several months, the model could drift away from an ice sheet's location by a few hundred kilometers, the researchers say.

This means the bears may be working harder, when moving against the direction of the ice, than scientists had 10: "Since we're underestimating the speed of drift, we're likely underestimating the energetic effort of polar bears," says Natasha Klappstein. The research reveals 11 insight into how highly mobile ice moves. As melting increases in the coming years, such ice will likely become more 12 farther north, in the central Artic. Scientists had known NSIDC data could underestimate drift speeds, but "any time we can find a data 13, it is a good thing."

Plus, such data could improve predictions about how oil spills or other pollutants may 14 in seas. littered with drifting ice, says Walt Meier, a senior NSIDC research scientist, who was not involved in the study. The findings may even 15 future NSIDC models: "It's a really nice data set," Meier says. "And certainly one we'll take under consideration."