填空题

According to the World Wildlife Fund, the polar bear could be faced with extinction and a large number of other animals reduced to very small remnant populations by global warming in Arctic regions.


Warmer winters are r 1 for the thinning or disappearance of ice sheets in many parts of the Arctic, 2 (result) in a situation where polar bears are at risk of 3 (starve) because they cannot travel to their normal breeding and hunting grounds.
Even in places 4 there is still a lot of ice around, polar bears are under threat because they rely on snow caves to rear their young. 5 of the warmer weather, some of these caves now collapse suddenly and bury the bear cubs inside.
Other effects of c 6 change are also being observed. Animals such as reindeer (known as "caribou" in North America) have adapted 7 the extreme cold and are therefore able to cope with the Arctic climate. For m 8 of years they have been migrating to places where they breed and find food. These 9 (migrate) coincide with the growing seasons of the plants they feed on. 10 (ecology) have found, however, that these animals are now arriving at their spring feeding grounds too late, and the 11 they eat have gone to seed. This is having a s 12 impact on caribou herds. A substantial number of calves are being lost and there is already a substantial 13 (reduce) in the size of the herds. Scientists are concerned, but 14 (power) to do anything in response to the situation—everything they have tried has been in vain. This is simply another unforeseen consequence of 15 (globe) warming.