There was a security officer next to me when I took the subject three, and some security officers were traffic police (I was invigilated by a first-class police inspector at the county level).

Some security officers are coaches of other schools. If you don't practice at all, it's basically cannon fodder, at least for a day or two.

Subject 3, also known as road test, is a part of motor vehicle driver's license test, and is the abbreviation of road driving skills and safe and civilized driving common sense test subjects in motor vehicle driver's test.

Different types of roads have different driving skills tests, which generally include: getting on the bus, starting, driving in a straight line, adding and subtracting gears, changing lanes, pulling over, going straight through intersections, turning left at intersections, turning right at intersections, crossing crosswalks, passing through school areas, passing bus stops, overtaking, turning around and driving at night.