平面截切正圆锥可能出现哪些情形？
题型：问答题 简答题
问题：
平面截切正圆锥可能出现哪些情形？
题型：问答题 简答题
第二节 完型填空（共20小题；每小题 1.5 分，满分 30 分）
阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
A ship hit a rock on its way back. The only 36 of the shipwreck was washed up on a small, 37 island. He prayed 38 for God to rescue him, and every day he scanned the 39 for help, but none seemed forthcoming.
Exhausted, he eventually managed to build a little hut 40 driftwood to protect him from the bad weather, and to store his few 41 . But then one day, after searching for food, he arrived home to 42 his little hut in flames, the 43 rolling up to the sky.
The 44 had happened; everything was lost.
He was shocked with grief and 45 . “God how could you do this to me!” he cried.
Early the next day, however, he was awakened by the 46 of a ship that was 47 the island. It had come to rescue him. "How did you know I was here?" asked the tired man of his 48 . “We saw your smoke 49 ,”they replied.
It is easy to get 50 when things are going bad.
But we shouldn't 51 
, because Nature is 52 in our lives, even in the midst of pain and 53 .
Remember, 54 your little hut is burning to the ground it just may be a smoke signal that summons the grace of Nature.
For all the negative things we have to say to ourselves, Nature has a 55 answer for it .
36. A. captain B. boss C. friend D. survior
37. A. lonely B. populated C. rich D. poor
38. A. happily B. feverishly C. sadly D. surprisingly
39. A. horizon B. sky C. land D. tree
40. A. by B. with C. out of D. in
41. A. possessions B. food C. furniture D. animals
42. A; look for B. find C. search D. search for
43. A. fire B. cloud C. smoke D. wind
44. A. best B. worst C. most D. least
45. A. sadness B. silence C. fear D. anger
46. A. sound B. voice C. whisper D. footstep
47. A. reaching B. arriving in C. approaching D. getting to
48. A. friends B. rescuers C. searchers D. brothers
49. A. sign B. mark C. scene D. signal
50. A. encouraged B. discouraged C. enabled D. disabled
51. A. lose heart B. lose our heart C. Lose a heart D. lose hearts
52. A. at work B. at play C. at large D. at table
53. A. blame B. suffering C. praise D. wandering
54. A. the first time B. the last time C. every time D. next time
55. A. wrong B. right C. different D. positive