A、Helping them acquire more knowledge. B、Restraining them from engaging in criminal activity. C、Tracing them when they escaped.

Stockbrokers, automobile dealers, mail carriers, insurance and real estate agents... have you ever imagined their fates?(33)The Internet will eradicate all these middlemen by the millions. Besides all these middleman jobs, other jobs that are considered very common and necessary, will disappear in the 21st century.
    The first will be the teacher.(34)Distance learning is becoming more popular through the miracle of online classes and electronic grading. People may never have to sit in a classroom and face the teacher, listening and taking notes any more. The only thing they need to do is to find a computer instead, but not go to school. The second will be the prison guard. A kind of sensor will be put into prisoners’brains.(35)The sensor will restrain prisoners from engaging in criminal activity. But now this technology still requires lots of improvements. The next will be truckers. There will be a kind of "smart" device set on both sides of roads that can enable all computer-driven vehicles to travel point to point at the same high speed, without any accidents. The printer may disappear, too. Magazines and newspapers will switch to digital paper. More and more people will be familiar with the E-magazine, E-newspaper, even E-shopping.
    In the end, maybe many years later, robots will become very common, like cars. Every family will own various kinds of robots to buy the food, to clean the home, and maybe, to take care of the children. Then, housekeepers can be liberated from housework forever.
33. What will cause millions of middlemen to disappear in the future?
34. How will people probably study in the future?
35. What can the sensor put into prisoners’ brains be used for?