Don't be surprised if you see a car going down the road without a driver in Beijing these days.In march, 2018, baidu was given a license to test its self-driving cars in Beijing, China Daily reported.

    Self-driving cars have been in development since 2010, when google announced that it was making such cars. Since then, companies like Tesla, Uber and Baidu have been working to produce and test their own self-driving cars.

    Self-driving cars are expected to change the way we get around. They are safer and more environmentally friendly than regular cars. They can remove the stress(压力) of driving and allow disabled or blind people to get around more easily.

    But self-driving cars have their own disadvantages as well. In one test, researchers pointed a laser pointer（激光棒） at the car's sensors（感应器） while it was moving. The car mistakenly thought that the laser beam（波束） was in its way and slowed down or changed directions.

    The software(软件) that is used to direct the cars may not be safe enough. Reported Live science. Sometimes, without any reasons,it may break down when we use our computers or smartphones. If the software in a self-driving car happened to crash. The results could be deadly.Maybe improvements to the software could solve this problem.

   To be a good teacher, you need some of the gifts of a good actor; you must be able to hold the attention and interest of your audience; you must be a clear speaker, with a good, strong, pleasant voice which is fully under your control; and you must be able to act what you are teaching, in order to make its meaning clear.
   Watch a good teacher, and you will see that he doesn't sit still before his class; he stands the whole time he is teaching; he walks about, using his arms, hands and fingers to help him in his explanations, and his face to express feelings.There are very important differences between the teacher’s work and the actor's.
   The actor has to speak words which he has learnt by heart; he has to repeat exactly the same words each time he plays a certain part, even his movements and the ways in which he uses his voice are usually fixed beforehand(预先).What he has to do is to make all these carefully learnt words and actions seem natural on the stage. A good teacher works in quite a different way. His audience take an active part in his play: they ask and answer questions, they obey orders, and if they don’t understand anything, they say so. The teacher can't learn his part by heart, but must invent it as he goes along.
   I have known many teachers who are fine actors in class but are unable to take part in a stage-play because they can't keep strictly to what another has written.

2016年8月和10月，我国在甘肃酒泉卫生发射中心相继成功发射了世界上第一颗量子卫星“墨子号”和神舟十一号载人飞船。相对于海南文昌卫星发中心，酒泉卫星发射中心的优势主要在于（    ）