阅读理解。
      
     Maybe your math teacher has already taught you how to find the center of a circle. It is not easy to
 learn and it takes some time to do so. Here is a way. First put a corner of a square piece of paper on a
 given circle and you will see the two sides the piece of paper meet the circle. And then you will get two
 points on the circle. You may name them Point A and Point B. Now draw a straight line through the Point
 A and Point B. You can get Line AB. Then, you must do the same thing a second time in a different place
  to get another two points, Point C, Point D and Line CD. You must write them down on the paper by
 yourself. You will find the center at once: the two lines cross at a point you may call it point O and this
 point is just the center of the circle. How about trying to see if it is easy to learn and remember this
 simple way of finding the center of a circle?
1. How many points are mentioned in the passage?
    A. Three      
    B. Five      
    C. Four
2. Which point is the center of the given circle?
    A. Point O        
    B. Point B      
    C. Point A
3. Does the center run through Line AB or Line CD?
    A. Line CD      
    B. Neither      
    C. Both
4. Which of the following is the right order to find the center of a given circle?
   a. Draw a straight line through the two points A and B.
   b. Do the same thing again in a different place.
   c. The two lines cross each other at a point.
   d. Put the corner of the square piece of paper on the given circle.
    A. a, b, c, d      
    B. c, a, b, d      
    C. d, a, b, c
5. When you use this way to find the center of a given circle, you need _____.
   A. a pencil, a square piece of paper and a pair of compasses
   B. a pair of compasses, a ruler and a square piece of paper
   C. a ruler, a pencil and a square piece of paper