问题 问答题

A、B两列火车在同一轨道上通向行驶,A车在前,速度为va=10m/s,B车在后速度为vb=30m/s因大雾能见度低,B车在距A车

600m时,才发现前方有A车,这时B车立即刹车,但要经过180m的距离B车才能停止.问

(1)B车刹车时的加速度大小为多少?

(2)A车若按原速前进,两车是否相撞,若会相撞,将在何时何地发生?

(3)B车在刹车的同时发出信号,A车在司机受到信号2s后加速前进,求A车的加速度满足什么条件才能避免事故发生?(不计信号传输时间)

答案
阅读理解

第二部分:阅读理解(第一节20小题,第二节5小题;每小题2分,满分50分)

  第一节:阅读下列短文, 从每题所给的四个选项 (A、B、C和D) 中, 选出最佳选项。

   Being the head of a high school for many years, I grew tired of budget meetings, funding cuts, and many other administrative chores (杂务). I started to dream of retirement. Sitting in traffic on a weekday morning, I would find my mind wandering. I would imagine spending time with my grandchildren, quiet evenings with my wife, traveling, or rediscovering some great books. I told myself that I wouldn’t sign myself up for any committees, any classes, or anything requiring a schedule.

  My first day of retirement came at last! I cooked a great breakfast for my wife and me, leisurely read the paper, cleaned a bit of the house, and wrote a few letters to friends. On the second day, I cooked breakfast, read the paper … On the third day, … This is retirement? I tried to tell myself that it was just the transition (过渡), that those golden moments were right round the corner, and that I would enjoy them soon enough. But something was missing.

  A former colleague asked a favor. A group of students was going to Jamaica to work with children in the poorest neighborhoods. Would I interrupt my newfound “happiness” and return to the students, just this once? One trip. That’s all. My bags were packed and by the door.

  The trip was very inspiring. I was moved not only by the poverty I saw but also by the sense of responsibility of the young people on the trip. When I returned home, I offered to work one day a week with a local youth organization. The experience was so positive that I was soon volunteering nearly full-time, working with students across North America to assist them in their voluntary work.

  Now, it seems, the tables have turnedSome days I am the teacher, other days I am the student. These young people have reawakened my commitment (责任感) to social justice issues by challenging me to learn more about the situation in the world today, where people are still poor and suffer because of greed, corruption and war. Most important, they have given me the opportunity to continue to participate in helping to find solutions. In return, I help them do their charitable projects overseas. I’ve gone from running one school to helping oversee the construction of schools in twenty-one countries!

  41. What did the writer expect to do after he retired?

  A. To stay away from busy schedules.

  B. To write some great books.

  C. To teach his grandchildren.

  D. To plan for his future.

  42. Why did the writer decide to go to Jamaica?

  A. He missed his students in that country.

  B. He couldn’t refuse his colleague’s favor.

  C. He was concerned about the people there.

  D. He was not satisfied with his retired life.

  43. The underlined part “the tables have turned” (Paragraph 5) means that the writer _________.

  A. improved the situation in his school

  B. felt happy to work with students again

  C. became a learner rather than a teacher

  D. changed his attitude toward his retired life

  44. What does the writer think of his retired life now?

A. Disappointing. B. Troublesome. C. Relaxing. D. Meaningful.

问答题 简答题