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如图所示，竖直平面内的3/4圆弧形光滑轨道半径为R，A端与圆心O等高，AD为与水平方向成45°角的斜面，B端在O的正上方，一个可看成质点的小球在A点正上方由静止开始释放，自由下落至A点后进入圆形轨道并恰能到达B点。求：
（1）到达B点的速度大小；
（2）释放点距A点的竖直高度；
（3）小球落到斜面上C点时的速度大小。
如图所示，竖直平面内的3/4圆弧形光滑轨道半径为R，A端与圆心O等高，AD为与水平方向成45°角的斜面，B端在O的正上方，一个可看成质点的小球在A点正上方由静止开始释放，自由下落至A点后进入圆形轨道并恰能到达B点。求：
（1）到达B点的速度大小；
（2）释放点距A点的竖直高度；
（3）小球落到斜面上C点时的速度大小。
请根据下列内容用英语写一篇报道。
1．杨杨（A）于2002年2月17日和23日在冬奥会上各获得了一块金牌，实现了中国在冬奥会的零的突破。
2．分别在女子500米短道速滑（short track speed skating）和100米决赛中获得冠军。
3．出生于中国东北的一个小城，14岁开始学短道滑，1995年加入国家队，1998年参加长野（Nagano）冬奥会并获得银牌。
4．在参加长野（Nagano）冬奥会后，本打算退役去接受正规教育，但为了在2002年的冬奥会上为祖国夺得金牌，就参加了2002年的冬奥会。
注意：1．报道必须包括所有列出的内容，可以适当增加细节。
2．字数在100—150之间。3．标题自拟。
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1．杨杨（A）于2002年2月17日和23日在冬奥会上各获得了一块金牌，实现了中国在冬奥会的零的突破。
2．分别在女子500米短道速滑（short track speed skating）和100米决赛中获得冠军。
3．出生于中国东北的一个小城，14岁开始学短道滑，1995年加入国家队，1998年参加长野（Nagano）冬奥会并获得银牌。
4．在参加长野（Nagano）冬奥会后，本打算退役去接受正规教育，但为了在2002年的冬奥会上为祖国夺得金牌，就参加了2002年的冬奥会。
注意：1．报道必须包括所有列出的内容，可以适当增加细节。
2．字数在100—150之间。3．标题自拟。
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
查看习题详情和答案>>
Having said goodbye to his parents, Alvin, with his wife and one-year-old son, set off back home. Still__36__ , Alvin and Clare talked and laughed happily. And even little Alax __37__ from time to time. The family were _38___ their trip.
But about three hours later things began to __39__ . It was starting to snow. Alvin __40__ up the car, hoping to arrive home before dark. But it was too dangerous to drive fast now. Because it was snowing more and more heavily. So Alvin had to __41__ down. The snow on the __42__ was getting deeper and deeper until it was hard to __43__ on it. Their car slipped(滑落) off the way and got __44__ in the deep snow and the engine refused to start again.
“The snow doesn’t seem to __45__. Shall we stay in the car waiting to be frozen to death or walk ahead through the snow?” Alvin asked. Clare said she __46__ to walk. So they got out of the car with their son and began walking. But __47__ was to come. Soon they lost their way and had to walk __48__ on and on.
Night came. They were not afraid of the dark. But they __49__ that poor Alax would die of cold. However, their faith to keep Alax __50__ filled them with courage, warmth and strength. They __51__ and rested in turn and then continued their walk. They had __52__ falls but each time true love encouraged them to rise to their feet again.
One, two, three, … seven days passed. On the eighth day, help at last came from Alvin’s __53__ , the police and local people. But the young __54__ had to have their feet cut off because of the bad frostbites(冻伤). __55__ , there was nothing seriously wrong with little Alax!
36. A. excited B. sorry C. worried D. anxious(急切的)
37. A. cried B. laughed C. smiled D. coughed
38. A. taking B. having C. enjoying D. starting
39. A. take place B. change C. come D. finish
40. A. climbed B. turned C. took D. sped(加速)
41. A. get B. slow C. go D. look
42. A. land B. highway C. fields D. car
43. A. walk B. depend C. stay D. wait
44. A. stuck (陷入) B. moved C. prepared D. covered
45. A. fall B end C. continue D. melt(融化)
46. A. liked B. prepared C.decided D. wished
47. A. better B. something C. nothing D. worse
48. A. hopelessly B. alone C. aimlessly D. pleasantly
49. A. thought B. feared C. expected D. were sure
50. A. happy B. silent C. alive D. dead
51. A. slept B. walked C. watched D. ate
52. A. a few B. several C. terrible D. countless(无数的)
53. A. friends B. parents C. neighbours D. brothers
54. A. husband B. wife C. couple(夫妇) D. baby
55. A. Therefore B. Finally C. Then D. Luckily
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