根据下列材料，回答46-50题
Virtual Driver
Driving involves sharp eyes and keen ears, analyzing with a brain, and coordination between hands, feet and brain. A man has sharp eyes and keen ears, analyzes through his brain, and maintains coordination (协调) between his hands and brains. He can control a fast-moving car with different parts of his body. 46 Apparently there isn't anyone in the driver's cab (驾驶室), but there is in fact a virtual driver. This virtual driver has eyes, brains, hands and feet too. The minicameras on each side of the car are its eyes and are responsible for observing the road conditions ahead of it as well as the traffic to its left and right. If you open the boot (行李箱), you can see the most important part of the automatic driving system: a built-in computer. 47 The brain of the car is responsible for calculating the speeds objects surrounding the car are moving at, analyzing their position on the road, choosing the right path, and giving orders to the wheel and the control system.
In comparison with the human brain, the virtual driver's best advantage is that it reacts quickly. 48 However, it takes the world's best racecar driver at least one second to react, and this doesn't include the time he needs to take action.
With its rapid reaction and accurate control, the virtual driver can reduce the accident rate on expressways considerably. In this case, is it possible for us to let it drive at any time and in any place? 49 With its limited ability to recognize things, the car can now only travel on expressways.
The intelligent car determines its direction by the clear lines that mark the lanes clearly and recognizes vehicles according to their regular shapes. 50 This being the case, people still have high hopes about driverless cars, and think highly intelligent cars are what the cars of the future should be like.
________________
A．Experts say that we cannot do that just yet.
B．In the near future, intelligent cars will be put into commercial operation.
C．This is the brain of the car.
D．But how does an intelligent car control itself ?
E．It completes the processing of the images sent by the cameras within 100 milliseconds.
F．However, it cannot recognize moving people and bicycles on ordinary roads that have no clear markings on them.
47、________________
A．Experts say that we cannot do that just yet.
B．In the near future, intelligent cars will be put into commercial operation.
C．This is the brain of the car.
D．But how does an intelligent car control itself ?
E．It completes the processing of the images sent by the cameras within 100 milliseconds.
F．However, it cannot recognize moving people and bicycles on ordinary roads that have no clear markings on them.
48、________________
A．Experts say that we cannot do that just yet.
B．In the near future, intelligent cars will be put into commercial operation.
C．This is the brain of the car.
D．But how does an intelligent car control itself ?
E．It completes the processing of the images sent by the cameras within 100 milliseconds.
F．However, it cannot recognize moving people and bicycles on ordinary roads that have no clear markings on them.
49、________________
A．Experts say that we cannot do that just yet.
B．In the near future, intelligent cars will be put into commercial operation.
C．This is the brain of the car.
D．But how does an intelligent car control itself ?
E．It completes the processing of the images sent by the cameras within 100 milliseconds.
F．However, it cannot recognize moving people and bicycles on ordinary roads that have no clear markings on them.
50、________________
A．Experts say that we cannot do that just yet.
B．In the near future, intelligent cars will be put into commercial operation.
C．This is the brain of the car.
D．But how does an intelligent car control itself ?
E．It completes the processing of the images sent by the cameras within 100 milliseconds.
F．However, it cannot recognize moving people and bicycles on ordinary roads that have no clear markings on them.