Accidents are caused; they don't just happen. In hindsight, the primary reason may be easy to see: an overloaded tray, a shelf out of reach, a patch of ice on the road. Still, there are often one or more human-related factors that lead to the misfortune, such as frustration, tiredness or bad temper. These factors show what an accident really is—a sort of attack on oneself. For example, road accidents, frequently happen after a family quarrel. We all know people who are accident-prone, so often at odds with themselves and the world that they seem to cause accidents for themselves and others. By definition(定义), an accident is something you do not intend to have happen. It is not always clear what sort of conditions make people more likely to have an accident. For instance, the law requires all factories to take safety precautions, and most companies have safety committees to make sure the regulations are observed. Despite this, every day in Britain, some fifty thousand men and women are absent from work due to injuries sustained in accidents. These accidents are largely the result of human error or misjudgment, and controllable factors such as fatigue, boredom or worry often contribute to them. Doctors who work in factories have found that those who drink too much(usually people who also have high anxiety levels) run three times the normal risk of accidents at work. This passage might be taken from ______.