填空题 Passage Nine Thirty-six years ago, when the grizzly was first listed as threatened, there were no bears along the Rocky Mountain Front, the plains at the base of the Rockies. If one was spied, it was routinely killed by ranchers. Now there are over a hundred, perhaps many more. A ---|||________|||--- of bears in their former habitat.

【正确答案】Appearance

【答案解析】本段主要讲了六十年前，当北美洲灰熊第一次被列入威胁者名单的时候，落基山脉下的平原根本就没有熊。如果某只熊被监视到，一般会被牧场主杀死。现在，这里可能要有多于百只的熊出没。最后一句话there are over...为我们提供了信息，由此我们可以总结出主题句应为熊以前的栖息地又开始出现熊类。答案额Appearance。