���˸߿�

　　Passage 3

　　We cannot feel speed. But our senses let us know that we are moving. We see things moving past us and feel that we are being shaken. We can feel acceleration， an increase in speed. But we notice it for only a short time. For instance， we feel it during the take off run of an airliner.

　　We feel the plane's acceleration because our bodies do not gain speed as fast as the seat. Actually， our bodies are trying to stay in the same place， while the plane is carrying us forward.

　　Soon the plane reaches a steady speed. Then， because there is no longer any change in speed， the feeling of forward notion stops.

　　1. We can tell that we are moving by ______.

　　A. watching things move past

　　B. feeling the speed

　　C. feeling ourselves being shaken

　　D. Both A and C

　　tell （在此处）分辨

　　2. Acceleration is the name for ______.

　　A. an increase in speed

　　B. a steady speed

　　C. any kind of movement

　　D. the movement of a plane

　　acceleration 加速度

　　increase 增加

　　steady 平稳的

　　3. During the take off of a plane， we feel that we are being ______.

　　A. thrown forward B. pushed back against the seat C. lifted out of the seat

　　D. pushed down into the seat

　　for instance 举例，例如

　　airliner 客机 take off 起飞 lift out 从……上面抬起来 push down 推下去，陷进去

　　4. We feel the plane's acceleration because out bodies gain speed ______.

　　A. just as fast as the plane B. faster than the planeC. more slowly than the plane

　　D. before the plane

　　5. The best title for this selection is ______.

　　A. The Takeoff Run of an Airliner B. Our Feeling of Speed

　　C. The Acceleration D. Speed Acceleration