题目

Not long ago, the only time you could see a robot was when you were reading a novel or watching a movie such as Star Wars (星球大战) . Today, however, a lot of things in science stories have been science facts. Robots are starting to appear in our everyday lives. These robots have different sizes, shapes, and colors. But they all have the same type of man-made “brain”. Leading the robot revolution （革命）are industrial(企业) robots that work in factories. Industrial（工业） robots can do different kinds of jobs that are often boring and sometimes dangerous. Robots are also c数轴上表示21-1的点A的位置应在（　　）A．2与3之间B．3与4之间C．4与5之间D．7与8之间