题干

如图所示,在一个水塘的表面均匀漂浮些鱼食,一只小鱼正在A处.现在小鱼在A处出发到水面取一点食物后,要回到岸边的B洞口处,请利用光学作图的方法,画出小鱼在这一过程中游动的最短路径(请保留作图中必要的辅助线)

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解:如图所示:

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       In Los Angeles, drivers spend sixty­one hours every year stuck in traffic. These drivers know too well how bad the traffic can be. “There're too many cars, and you can't move around a lot.”

       Professor Cyrus Shahabi also knows about traffic jams. He lives more than 65 kilometers from his office at the University of Southern     California in Los Angeles. He is always late even with the help of a navigation (导航) system.

       He decided to develop a program called ClearPath for that. He says his program uses historical data to predict traffic conditions even before the driver leaves the house.

   “What's unique is that we use a lot of data that's currently become available including traffic data, weather data, and we analyze that so that we can predict what's going to happen in front of you when you leave home.”

      Professor Shahabi says his system does more than just respond to current traffic conditions. With ClearPath, he says, a driver can decide what time he wants to leave, and ClearPath will give the fastest route. It looks at the entire road network, including surface streets as well as highways, before the driver hits the road. Professor Shahahi hopes to have ClearPath available nationwide and overseas once they can collect traffic data from other cities.

   “I always thought that Los Angeles had the worst traffic, but now I know that Shanghai, Beijing, Seoul, Tokyo, believe it or not, Singapore, Hong Kong certainly are examples that can immediately use this.”

       Professor Shahabi hopes to share this new technology with companies that already have navigation systems, such as Google and Apple.