2020-2021学年高一英语牛津译林版(2020)必修第三册Unit1 Period Four Writing 课时作业

Period Four　Writing Ⅰ.语篇填空 Polar bears are suffering in a 1.　　　　　　 (warm) world than ever before. Polar bears live in environments too cold for most animals. During much of the year, they live and hunt on the 2.　　　　　　 (freeze) Arctic sea ice. Nature has prepared the bears for the cold conditions but nothing has prepared them for the danger that 3.　　　　　　 (threat) the only home they know. The scientists have drawn a 4.　　　　　　(conclude) that the polar bears’ world is melting. Studies show that the polar ice has reduced 5.　　　　　　 9.8% every 10 years since 1978. Now about 20,000 to 25,000 polar bears live in the Arctic. Polar bears depend on the sea ice for their 6.　　　　　　(survive). “The sea ice is more than just this platform that the bears walk over.” As Andrew Derocher, a scientist who studies North American polar bear populations puts 7.　　　　　　, “Only 8.　　　　　　 polar ice melts quite slowly can they survive on the Earth.” Some melting and refreezing of the polar ice is natural. But in a warme