题目

阅读理解 Recently, researchers revealed details on several tiniest robots they have created. Small enough to sit on the side of a penny, the robots can be controlled by a laser(激光). The tiniest is shaped like a crab(螃蟹)and is just half a millimeter wide. The robots don't have any power of their own. Instead, they can be controlled from a distance by using lasers. The researchers say the robot is designed a bit like a 3D pop-up book. The basic shape for the crab is flat. The flat shape is then attached to a rubbery material that's stretched out. When the rubbery material is allowed to relax, the robot pops up into a standing crab. This mixture of layers is the secret to the crab's movement. The different layers give the material two positions that it can be in. When the hard glass layer is softened, the rubbery layer bends the material. But when the hard layer hardens again, it turns back to its old position. The scientists call this "shape-memory". The trick to getting the hard glass layer to soften is to warm it up with a laser. Because the robots are so tiny, their parts heat up and cool down very quickly. By warming up different parts of the robots, scientists can make them move in different ways. The researchers say their robots can climb, walk, turn, and even jump. The robots aren't super speedy. But given their tiny size, they're also not too slow. It takes the crabs about 20 seconds to cover 1 centimeter. Right now the robots aren't all that useful. All they can do is move, and they need to be in a place where lasers can shine on them to do that. But scientists say that one day tiny robots like these might be able to work in very small spaces. It's possible that they could build very tiny machines, or perhaps even travel inside the human body to help deal with medical problems. （1） What do we know about the tiniest robots? A . They are produced by 3D printing. B . They have the size of a penny. C . They can be remotely controlled. D . They need no energy to move. （2） What does the author intend to do in Paragraph 2? A . Provide information about rubbery materials. B . Analyze the working process of laser. C . Introduce the concept of shape-memory. D . Explain the way to make the robot move. （3） What should be improved about the tiniest robots? A . Their use. B . Their apps. C . Their power storage. D . Their moving directions. （4） What is the best title for the passage? A . Robots without energy consumption B .  World's tiniest remote-control robots C . Flexible tiniest robots in our body D . Crab-like robots for the future 答案： C D A B

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