What will the car be like in the future？Maybe we can sit in a car that can drive itself．

About 40years ago，scientists from the United States started to develop self-driving cars （无人驾驶汽车）．The most famous recent one was made by Google in 2009．There are cameras and radars （雷达） on the top of the car．They allow the computer in the car to draw a 3D map of the environment．Chinese scientists have also successfully developed a self-driving car．The car made a trip from Changsha to Wuhan．

Is a self-driving car safe？A recent study shows that robots make safer drivers than humans．If only 10% of cars on the street are self-driving，they will save 1，000lives （生命） every year．If 90% of vehicles （交通工具） are self-driving，21，700lives will be saved a year．However，a self-driving car is expensive and each costs about $100，000．So it is impossible to be very popular in the near future．

根据短文内容，判断下列句子正误．正确的用“A”表示，不正确的用“B”表示．

31．American scientists started to develop self-driving cars in 2009．___

32．Cameras and computers are on the top of the self-driving car by Google．___

33．In China，scientists have successfully developed a self-driving car．___

34．The more self-driving cars there are on the street，the fewer traffic deaths there will be．___

35．The self-driving cars will be very popular in the near future．___．