A、There is a sign of "green hand" inside the car. B、There are two sets of brakes inside the car. C、It is only big enough to hold

[16]In America, driver’s education is part of the regular high school curriculum. Every student in his or her second year of high school is required to take a class in driver’s education. However, unlike other courses, it is not given during the regular school year. Instead it is a summer course.
    The course is divided up into two parts: class time for learning laws and regulations and driving time to practise driving. Class time is not unlike any other class. The students have a text from which they study the basic laws they must know. Driving time is a chance for the students to practise starting steering, backing up, parking, switching lanes, turning comers, and all the other maneuvers required. Each student is required to drive a total of six hours. The students are divided up into groups of four. The students and the instructor go out driving for two hours. Thus, each student gets half an hour driving time per outing. The instructor and the "driver" sit in the front seats and the other three students sit in the back.
    Driver’s education cars are unlike other cars in which they have two sets of brakes, one on the driver’s side and one on the other side where the instructor sits. Thus, if the student driver should run into difficulties the instructor can take over. The car also has another special feature. On the top of the car is a sign that reads: STUDENT DRIVER. That lets nearby drivers know that they should use extra caution because the student driver is not very experienced and prone to driving slowly.
16. What is special about the driver’s course in America?
17. What can students learn during class time?
18. How is the driver’s education car designed in order to prevent accident?