Robots seem very new to most people. But they have a 1 history. A Greek scientist made the first robot. You may 2 robots in some movies. The robots in the movies are usually stronger, faster and 3 than people. In real life, most robots are used in factories. They can do lots of dangerous, difficult or4 jobs. Some people can't look 5 themselves and robots can help them. For example, some people can't see, and they use a guide dog to help themselves move. But now scientists are making a 6 to help them.

    Robots are also used in American hospitals. At one hospital, a robot 7 meals from the kitchen to the sick people's rooms. It never loses its 8 because it has a map of the hospital in its computer system(系统). 9 the future, robots will even work in space. But robots will 10 take the place of(代替)people but only work for people. They can, however, help us in a lot of different ways.

质量为m的物体在水平力F作用下由静止开始在光滑地面上运动，前进一段距离之后速度大小为v，再前进一段距离使物体的速度增大为3v，则（   ）