A young woman carrying a three-year-old child got on a bus. The conductor hurried to give her a warm welcome and then kindly asked the other passengers to make more room for the woman and her child. On seeing this, people began to talk. "You know this conductor used to be very rude. Now suddenly he has changed his bad behavior , "said a middle-aged man.
"Yes, he should be praised and we must write a letter to the company," said a second passenger. "That's right," another lady said, "I wish a newspaper reporter were here so that more people could learn from this conductor. "
Just then a gentleman who looked like a teacher turned to the conductor and said , "Excuse me, but can I know your name, please? Your excellent service must be praised..."
Before he could open his mouth, the three-year-old child sitting on the young woman's lap interrupted, "I know his name. I call him Dad."
56. One passenger suggested writing a letter to the company to ______ .
A. make a demand for more buses B. thank the conductor for his good service
C. criticize the conductor for his rude behavior
D. invite a newspaper reporter to write about the conductor
57. What was the gentleman?
A. A teacher. B. A newspaper reporter.
C. Not known from the story. D. The conductor's friend from his company.
58. The word "him" in the last paragraph refers to _______.
A. the gentleman B. the conductor C. the middle-aged man D. the three-year-old child
59. It is clear from the story that the conductor _______.
A. has changed his attitude towards his work B. has now been kind and polite to all passengers
C. has not changed his rude behavior to passengers
D. has now been kind and polite to women with children
为从顶点i到顶点j的一条最短路径的权重。
；当k＞0时，该最短路径上所有的中间顶点均属于集合1，2，…，k。
；若中间顶点不包括顶点k，则
。
给出了任意两个顶点之间的最短路径，即对所有i，j∈V，
表示顶点i到顶点j的最短路径。