Hello, teacher, it is strictly forbidden to get on the third grade of passenger vehicles. What does third grade mean?

Refers to dangerous goods, flammable and explosive goods, toxic and harmful goods.

Any public transportation should be of these kinds

These include items that are prohibited or restricted from transport by the state; dangerous goods specified in laws, regulations, and rules, such as Fireworks, firecrackers, gasoline, kerosene, alcohol, banana water, paint, film, various glues containing perchlorethylene, acrylates, chloroprene, phenolics, polyurethane and other ingredients and chemical products whose nature cannot be determined by the carrier; animals and items that impede public health, including items with foul odors and other odors; items that can damage or contaminate vehicles.