完形填空(共20小题，每小题1.5分，满分30分)
阅读下面短文，掌握其大意，然后从36～55各题所给的四个选项（A、B、C和D）中，选出最佳选项。
A certain good woman one day said something that hurt her best friend of many years. She __36__ immediately and would have done anything to have taken the words back. What she said __37__ her friend so much that this good woman was hurt herself for the pain she caused. In a(an) __38_ to undo what she had done, she went to an older, wiser woman in the village to ask for 39 .
Listening to her, the older woman __40__ the younger woman’s great pain and knew she must help her. She __41__ knew she could never ease her pain, __42__ she could teach. She knew the result would depend only on the __43__ of the younger woman. She said, “Tonight, take your best feather __44__ and put a single feather on the doorstep of each __45__ in town before the sun rises.”
The young woman __46__ home to prepare for her words, even if the feather pillow were very dear to her. All _47__ long, she worked alone in the cold. __48__ the sky was getting light and she placed the last feather on the steps of the last house. Just as the sun rose, she _49__ to the older woman.
“Now,” said the wiser woman, “Go back and refill your pillow with the __50__ you have put on the steps. Then everything will be as it was before.”
“You know that is __51__ ! The wind blew away each feather as fast as I put them on the doorsteps!”The young woman was very __52 _ .
“That is true, ” said the older woman. “Never __53_ . Each of your words is like a feather in the wind. _54_ spoken , no effort can ever return them to your mouth. __55__ your words well and guard them most of all in the presence of those you love.”
36. A . called B. apologized C. regretted D. wrote
37. A. hurt B. missed C . impressed D. gave
38. A. effect B. effort C. letter D. offer
39. A. view B. money C. comfort D. advice
40. A. sensed B. reminded C. noticed D. reduced
41. A. hardly B. still C. also D. yet
42. A. so B. and C. for D. but
43. A. patience B. attitude C. character D. words
44. A. coat B. cap C. quilt D. pillow
45. A. stair B. house C. gate D. street
46. A. hurried B. drove C. rode D. walked
47. A. day B. morning C. night D. afternoon
48.A. Again B. Finally C. Suddenly D. lately
49. A. referred B. turned C. returned D. devoted
50. A. sand B. money C. step D. feather
51. A.useless B . impossibe C. unnecessary D. boring
52. A .surprised B. right C. puzzled D. angry
53. A. admit B. mind C. remember D. forget
54. A. Once B. Though C. Unless D. As
55. A. Speak B. Choose C . Say D. Guide
和功的公式W=Fs，结合速度公式，分析求解．推土机的牵引力做的功：W=F•s又∵
∴
．当推土机以额定功率进行推土作业时，