The two-seater car has a cute,round shape.Its front end looks like a friendly face:The “eyes” are headlights,the “nose” is a laser sensor and radar.

　　Another group of radars,lasers and cameras sits on top of the roof and gives the cars a 360-degree “view”.They are linked to computer software that can identify people,cars,road signs,and traffic lights,and thus tell the car to make turns and stops.

　　But the driverless car is only a “fair weather friend”,the DailyMail commented.

　　According to the MITTechnologyReview,the current driverless cars can’t react like a human driver.They can’t drive in heavy rain or snow.

　　Chris Urmson,director of the Google car team,said that this is because the detection technology is not yet good enough to separate certain objects from weather conditions.In the cars’ “eyes”,raindrops and snowflakes are the same as rocks,and cars stop for them.But if the manhole (下水道入口) ahead is uncovered,they drive over it without hesitation.Also,if a police officer waves at the side of the road to ask traffic to stop,the cars cannot understand him.

　　Despite all these problems,Urmson said driverless cars will “happen more quickly than people think”—perhaps as soon as in five years’ time.

　　But even at that time,driverless cars won’t be truly “driverless”.

　　In the US,driverless cars are only allowed on roads in certain states if someone sits in the driver’s seat.

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