题目

有如下VB程序段：s=0For k =3 To 1 Step-1 If k <=1 Then x=1 If k <=2 Then x=2 If k <=3 Then x=3 s=s+xNext kText1. Text= Str(s)该程序段运行后，文本框Text1中显示的内容是（ ） A . 9 B . 7 C . 6 D . 5 答案：A (07·四川D篇) Sorry to say, our brains naturally start slowing down at the Cruelty young age of 30. It used to be thought that this couldn't be helped, but new studies show that people of any age can train their brains to work faster. "Your brain is a learning machine," says University of California scientist Dr. Michael Merzenich. Given the right tools, we can train our brains to act like they did when we were younger. All that's required is the practice designed just for the purpose: a few exercises for the mind. Merzenich has developed a computer-based training method to speed up the process(过程)                         in which the brain deals with information (positscience.com). Since much of the data we receive comes through speech, the Brain Fitness Program works with language and hearing to better speed and accuracy (准确性). Over the course of training, the program starts asking you to distinguish (辨别) sounds (between "dog" and "bog", for example) at an increasingly faster speed. It's a bit like tennis instructor, says Merzenich, hitting balls at you ~faster and faster to keep you challenged(受到挑战). You may start out slow, but before long you're pretty quick. The biggest finding in brain research in the last ten years is that the brain at any age is highly plastic. If you ask your brain to learn, it will learn. And it may even speed up while in the process. To keep your brain young and plastic you can do one of a million new activities that challenge and excite you: playing table tennis or bridge, doing crossword puzzles, learning a language.... "When it comes to preventing ageing, you really do 'use it or lose it' ," says Barbara Sahakian, professor at Cambridge University. 67. Dr. Merzenich’s training method mainly depends on ________. A. speech training                             B. computer languages    C. the activities one joins in               D. the information being dealt with 68. By saying "the brain at any age is highly plastic ", the writer probably means the brain can be______.     A. used              B. mastered        C. developed             D. researched 69. What can we learn from the text?     A. Practice makes a quick mind.     B. Brain research started ten years ago.     C. Dr. Merzenich is a scientist in computer,     D. People believed nothing could stop the brain slowing down. 70. Which of the following agrees with the writer's idea?     A. The training methods work better for the old.     B. People should use the brain to stop it from ageing.     C. The training of the brain should start at an early age.     D.  It's necessary to take part in as many activities as possible.