新版新概念英语第二册_高中新概念英语语法填空：Polar,bears

新概念英语网权威发布高中新概念英语语法填空：Polar bears，更多高中新概念英语语法填空相关信息请访问新概念英语网。

阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填人一个适当的词或使用括号中词语的正确形式填空，并将答案填写在答题卡标号为31～40的相应位置上。

　　Polar bears are suffering in a 31 (warm) world.

　　Polar bears live in environments too cold for most animals. 32 much of the year, they live and hunt on the frozen Arctic sea ice. Nature has prepared 33 for the cold conditions. But nothing has prepared the bears for the danger that 34 (threat) the only home they know.

　　The polar bears’ world is melting. Studies show that the polar ice has reduced by 9.8% every 10 years 35 1978. Now about 20,000 to 25,000 polar bears live in the Arctic. Polar bears depend on the sea ice for their 36 (survive). “The sea ice is more than just this platform that the bears walk over,” says Andrew Derocher, 37 scientist who studies North American polar bear populations. “ 38 it, they can’t exist.”

　　Some melting and refreezing of the polar ice is natural. 39 in a warmer world, these cycles speed up, and bears have less time to hunt. Normally, they have three months in the spring when they gain more weight. The extra fat is used later, 40 the bears are not actively hunting.
　　31.warmer 32.For/During 33.them 34.threatens 35.since 36.survial 37.a 38.Without 39.But 40.when