题目

将抛物线y=x2﹣1向左平移2个单位，再向上平移2个单位，得到的抛物线解析式为（ ） A．y=（x+2）2+1 B．y=（x﹣2）2﹣1   C．y=（x﹣2）2+1 D．y=（x+2）2﹣1 答案：A【考点】二次函数图象与几何变换． 【分析】先确定抛物线y=x2﹣1的顶点坐标为（0，﹣1），把点（0，﹣1）向左平移2个单位，再向上平移2个单位到的点的坐标为（﹣2，1），然后根据顶点式写出平移后抛物线的解析式． 【解答】解：抛物线y=x2﹣1的顶点坐标为（0，﹣1），把点（0，﹣1）向左平移2个 It was an early morning in summer. In the streets, sleepy-eyed people were moving quickly, heading towards their ___1___. This was the beginning of another ___2___ day in New York City. ___3___this day was to be different. Waiting ___4___ the crowded streets, on top of a ___5___ 110 stories high, was Philippe Petit. This daring Frenchman was about to ___6___ a tightrope(绷索) between the two towers of the World Trade Center. Philippe took his first ___7___ with great care. The wire held. Now he was ___8___ he could do ___9__ only a balancing pole. Philippe walked his way across, a ___10___ of 131 feet. Soon the rush-hour ___11___ began to notice. What a ___12___! There, 1350 feet above the street, a ___13___ figure was walking on air. Philippe made seven ___14___, back and forth(来回). He wasn’t satisfied with just ___15___. At times he would turn, sit down, and ___16___ go on his knees. Once, he had the astonishing ___17___ to lie down on the thin thread. And thousands of ___18___ watchers stared with their hearts beating fast. After the forty-five-minute ___19___, Philippe was taken to the police station. He was asked ___20___ he did it. Philippe shrugged(耸肩) and said, “When I see two tall buildings, I walk.” 1. A. job B. homes C. buses  D. offices 2. A. working B. hot     C. same   D. ordinary 3. A. And       B. So      C. But     D. Thus 4. A. for  B. in       C. by      D. above 5. A. roof       B. position      C. wall    D. building 6. A. throw     B. walk   C. climb  D. fix 7. A. act  B. landing      C. step    D. trip 8. A. sure       B. uncertain    C. glad    D. nervous 9. A. Through B. Against      C. With   D. On 10. A. distance       B. height C. space  D. rope 11. A. streets   B. crowds       C. passengers  D. city 12. A. height  B. pleasure     C. wonder      D. danger 13. A. great    B. strange       C. public D. tiny 14. A. experiment  B. circles C. trips    D. movements 15. A. walking       B. staying       C. acting D. showing 16. A. almost  B. even   C. often   D. rather 17. A. spirit    B. result  C. strength      D. courage 18. A. patient  B. terrified     C. pleased       D. enjoyable 19. A. show    B. trick   C. try      D. program 20. A. how     B. why    C. whether      D. when