A、The drivers could read newspaper in cars. B、The cars join. C、The drivers switch over to Minigap. D、The car could leave at will

When a man is driving a car for long distances along a main road or motorway, two of his problems are to keep the car at a fairly steady speed and to make sure that he does not run into the car in front of him. Easy enough you may think—but it is even easier on long motorway drive for a man’s attention to wander. Some experiments have been made with a system, which involves computer control of these two problems. The car’s computer keeps the speed steady. At the time the distance between the car and another car in front it is rear reflectors of the car in front and is reflected back, so enabling the distance to be measured. This information is fed to the computer, which adjusts its speed control accordingly.
    There are also to be experiments with a system called "Minigap". This system will be particularly useful to drivers stuck in long queues of cars, as the computer would control not only the speed and the distance from the car in front, but also the steering. Using this system, a driver could switch over to Minigap, take out his newspaper and do the crossword puzzle while car drives most of the way home automatically. To the roadside observer, the line of cars would seem like a train which carriages could join or leave at will.