下列有关兴奋在神经纤维上的传导的叙述，不正确的是（　　）

近来，公共舆论中心出现了一种值得思考的“被就业”“被增长”“被自愿”等“被”现象。如所谓“被增长”，也就是说实际没有增长，但在统计数据中却增长了，使我们都被统计数据“幸福”地笼罩着。越来越多的“被”现象对政府的启示是

如图中，a、b、c三条图线表示三种质量相等的固体同时同等条件下加热时的熔化图像，由图可知   （    ）

    In some science fiction movies, evil robots refuse to die, no matter how hard people fight back.
    Now science fiction has become science fact. For the first time, scientists have made a robot that can take a beating and keep on going. Scientists from Cornell University made the robot, which looks like a spider with four legs.
    Until now, even the most advanced (先进的) robot was almost certain to break down when it was damaged (毁坏). That is because its computer inside simply doesn't know how to make the machine work after its shape has changed. 
    To deal with this problem, the scientists put eight motors (发动机) and two sensors (传感器) that read how the machine is working. They all give signals to the machine's software. Using this information, the computer can then figure out the machine's shape at any moment.
    The new technology is a big advance in robot-making, scientists say, and it's far from scary. It may someday help scientists create better artificial (假的) arms and legs and give new freedom to people who lose them. It might also help scientists understand how people and animals figure out their own sense of place in space.
    “It has been difficult to design robots that can work well when the environment changes or when it's damaged,” says Olaf Sporns of Indiana University in US. “With this work, we are nearer to solving this problem.”

读下表我国某地区地形类型比例以及土地利用现状图，该地区耕地比重过高，容易造成的环境问题是（    ）。