园艺上常根据什么原理进行果树整枝修建？

Small moments sometimes last a very long time. And a few words—though they mean    21  at the time to the people who say them—can have great power.
I recently heard a story from Malcolm Dalkoff, who has been a professional   22 for the last twenty-four years, mostly in advertising.
As a boy, Dalkoff was terribly shy and    23  . He had few friends and no self-confidence. Then one day, his high-school English teacher, Ruth Brauch, asked the class to write their own chapter that would    24    the last chapter of the novel since they had been reading To Kill a Mockingbird. Dalkoff wrote his chapter and turned it in. Today he cannot recall anything special about the chapter he wrote, or what    25  Mrs. Brauch gave him.   26   , what he does remember is the four words in the paper: “This is good writing.” Four words. They    27  his life.
“Until I read those words, I had no idea of who I was or what I was or what I was going to be,” he said, “After reading her    28   ,I went home and wrote a short story,   29  I had always dreamed of doing but never believed I could do.”
Over the rest of that year in school, he wrote many short stories and always brought them to Mrs. Brauch for instruction. “She was    30  , helping and honest. She was just what I needed,” Dalkoff said. 

21	A. much	B. little	C. well	D. ill
22	A .report	B. designer	C. writer	D. teacher
23	A .weak	B. independent	C. troublesome	D. helpless
24	A. follow	B. change	C. connect	D. explain
25	A .help	B. encouragement	C. grade	D. words
26	A. Therefore	B. However	C. Meanwhile	D. Besides
27	A .improved	B. developed	C. changed	D. enriched
28	A. chapter	B. novel	C. note	D .explanation
29	A. everything	B. something	C. nothing	D. anything
30	A. encouraging	B. careful	C. strict	D. effective