目前，可可西里自然保护区鼠害严重，在1平方米的范围内就有十几个被老鼠掏空的洞。被鼠类危害过的草地变成了“鼠荒地”，草皮遭到严重破坏，草场退化甚至沙化。可可西里自然保护区平均海拔4600米以上，作为地表生态屏障的草皮，原本就是在冻土地带勉强成活，而现在一只青海田鼠一年就要吃掉60千克的鲜草。如不及时治理鼠害，藏羚羊、藏原羚等国家一、二级保护动物的生存环境和保护区的生态链条都将面临严峻的考验。据此回答：

危害该自然保护区的鼠类属于(   )

    Do you know Stephen Hawking? He's one of the most well-known____（scientist）on space and time in the world. He was born in England in 1942. Hawking is ____（study）how the universe began and how it ends.

    When he studied math and science at Oxford University, he fell____(serious) ill, which made him unable to speak or breathe. Till now, he can't move or feed____(him). however, he has a wheelchair with ____ special computer, with which he can communicate with others.

    ____he was facing all these difficulties, he refused to give up his hope of living. Because____ his illness, it was difficult for him to draw diagrams or to write. So he started____(think) in pictures. With this new way of thinking, he is respected by people in the world.

    Once he____(invite) to China to give lectures. His self-confidence and humorous conversations impressed us deeply.

    He once said, “When something unfair happens,____ is no need to worry about it! You just have to do the best in your own situation.”

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