The main factors that determine a person's blood alcohol concentration (BAC) are how much alcohol has been consumed, how quickly it was consumed, and the person's body weight.

Parking brakes should be used whenever you park. If necessary, chock your wheels.

During the vehicle inspection test, you will be required to do a complete inspection of your vehicle. During this inspection, you must explain to the examiner what you are inspecting and why you are inspecting those items.

Before coupling together a tractor and a trailer, you should make sure the trailer is at the proper height. If the trailer is too low, the trailer nose may be damaged. If the trailer is too high, it may not be able to couple correctly.

The stab braking method for emergency stops involves fully applying the brakes until they lock up. The brakes are then released until the wheels start rolling, and then the process is repeated.

B:C fire extinguishers are designed to work on electrical fires and burning liquids. Don't pour water on an electrical fire.

When doing a pre-trip inspection during the winter, you should pay extra attention to the coolant level and amount of antifreeze; the defrosting and heating equipment; the wiper blades and windshield washer; the tires and tire chains; the lights and reflectors; the windows and mirrors; the hand holds, steps, and deck plates; the radiator shuttles and winterfront; and exhaust system.

Before a trip, ensure that air in the air brake system reaches all trailers. Do this by waiting for air pressure to build, then sending air to both the emergency and service lines and opening the shut-off valves on the rear of the last trailer. If air escapes from the shut-off valves in the rear of the combination, the air is being supplied to the entire vehicle.

The best thing to do when confronted with an aggressive driver is to get out of their way, if possible. Avoid making eye contact, which could further provoke the driver. Ignore any hand gestures made by the driver.

Shippers package hazardous materials in a way that is meant to completely contain the materials. Vehicles should be placarded to communicate the risk of the cargo.

Factors that affect how much liquid is safe to load into your tank include how much the liquid will expand in transit, the weight of the liquid, legal weight limits, and the temperature of the load.

In heavy traffic, it is safest to travel at the same speed as other vehicles. If two vehicles continue to drive in the same direction at the same speed, they cannot hit each other.

When driving on a wet road surface, the risk of hydroplaning is increased if your tire pressure is too low or your tire tread is too worn. If you begin to hydroplane, release the accelerator and push in the clutch to slow down.

It is always important to have enough water and antifreeze in a vehicle's cooling system. Despite the name, antifreeze is beneficial to an engine even in hot weather.

All commercial motor vehicles are required to be equipped with the proper emergency equipment. This may include spare electrical fuses; three red reflective triangles, six fuses, or three liquid burning flares; and at least one properly charged and rated fire extinguisher.

Fighting a hazardous materials fire requires special training and protective gear. Unless you have the proper equipment and training, do not try to fight a hazardous materials fire yourself.

Driving at night is more dangerous than driving during the day because hazards become more difficult to see in the dark.

Rough acceleration can cause mechanical damage, so be sure to accelerate smoothly and gradually.

Distracted drivers perceive hazards on the road more slowly than drivers who are focused, or they do not perceive hazards at all.

Tires should never have too much air pressure. Be sure to check your tires' air pressure with a gauge during inspections.