题目

阅读理解 Electric cars are supposed to help the world go green and stop hurting the planet. Engineers at Brown University and the University of Maryland are taking that goal to another other level, with a new idea for batteries made from trees, according to new findings published in Nature. Lithium-ion batteries (锂电池) have become the new form of rechargeable batteries thanks to their extraordinarily long charge. You're probably reading this story from a device powered by such a battery. Most electric cars like ones made by Tesla use lithium-ion batteries. These batteries use a liquid solution that conducts lithium ions from the battery's cathode and anode (阴极和阳极), but the liquid is not what helps ensure electrical power goes from the battery to the device it's powering. The problem is that this liquid is made of harmful materials that are sometimes unstable. They sometimes have explosive results. A solid conducting structure would prevent this from happening, but it could be likely to crack and break, making the battery useless. An ideal material for solid state lithium-ion batteries would be thin and flexible to resist structural stresses, and it is wood from a tree. The team in charge of the new research developed a mixed material made of copper (铜) and fibers coming from wood. They tested it out as a model for conducting ions back and forth in a lithium-ion battery, and found it works 10 to 100 times better than other solid-state conductors-a record high. The new findings are just based on basic model tests, and a rechargeable battery made of trees is still quite a way off. But if it passes test as a practical form of energy, it can very well replace rechargeable batteries. It is not hard to imagine electric cars having better sales for their real green, but saying that their batteries are just made from trees is beyond our imagination. （1） How are engineers making electric cars greener according to the text? A . By improving the materials of batteries. B . By reducing lithium ion in the batteries. C . By using liquid to conduct electric power. D . By producing more lithium-ion batteries. （2） What is the advantage of lithium-ion batteries? A . They contain eco-friendly liquid. B . Their charge lasts for a long time. C . They offer electrical power stably. D . They are safe and unlikely to explode. （3） Why is wood chosen as the solid-state conductor? A . It is resistant to structural pressures. B . It is much thicker and less changeable. C . Its copper and fibers conduct ions well. D . It proves to be a practical form of energy. （4） What can we infer about batteries made of trees from the last paragraph? A . They have taken effect for a long time. B . They are still being tested at present. C . They will never replace current batteries. D . They will make electric cars hard to sell. 答案： A B A B

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