题目

已知线段AB＝5 cm，在AB的延长线上取一点C，使AC＝AB，在AB的反向延长线上取一点D，使DA＝AB，那么线段CD的长度是( )A. 9 cm B. 10 cm C. 11 cm D. 12 cm 答案：【答案】C【解析】分别求出DA、AC的长即可求解.如图，∵AB=5cm，AC＝AB，∴AC=9cm，∵DA＝AB，∴DA=2cm，∴CD=AC+AD=9+2=11cm.故选C.4、       Scientific mistakes can live on forever. When 18th-century European museums were first sent specimens of a large furry animal with long curved white claws, they named it“bear-like sloth（树獭）”because its claws resemble those of South American sloths. Later scientists realized that the species was a tropical bear unrelated to sloths, but its wrongheaded name remains the sloth bear.        Ranging India, Nepal, Bhutan, Sri Lanka, and possibly Bangladesh, these 150 to 300-pound bears feed on fruits and insects. They sound like bellows（公牛吼叫）when using their flexible noses and lips to blow away dirt and suck up ants. But don’t be misled: This gentle-looking bear can be dangerous, occasionally killing villagers who enter the forest. Yognand often talks with villagers to help avoid conflicts.“Attacks can be prevented if people avoid certain places.”        One goal of his research has been to track a dozen radio-collared bears in the dry forests of India’s Panna National Park. He’s discovered that some bears have home ranges of up to 40 square miles. His conclusion：“We need to protect large patches（地盘）of their habitat and maintain links between those patches. Unfortunately sloth bears have to compete with species such as tigers. The bears get far less attention than they deserve.” 60．The large furry animal was named the sloth bear because        .        A．it has something to do with the sloth        B．its claws look like those of South American sloths        C．it has long curved white claws        D．it looks like bears 61．Sloth bears usually live in       .        A．East Africa                                          B．South America        C．cold regions                                        D．South Asia 62．The underlined word“habitat”in the last paragraph probably means       .        A．the dry forest                                       B．a national park        C．the natural home of an animal                D．the wet land 63．The author writes this article in order to       .       A．call on people to pay more attention to the kind of bear        B．ask people to avoid conflicts with such kind of bear        C．warn people to be far away from the bear        D．tell us an interesting story