A person or thing that closely resembles another, as in Our grandson is a carbon copy of his dad. Originally this term meant a copy of a document made by using carbon paper. The linguistic transfer to other kinds of duplicate survived the demise of carbon paper (replaced by photocopiers, computer printers, and other more sophisticated devices). [ c. 1870 ]
The severity of symptoms depends on whether the injury is mild, moderate or severe. 1  Mild traumatic brain injury, also known as a concussion, either doesn't knock you out or knocks you out for 30 minutes or less. 2  Moderate traumatic brain injury causes unconsciousness lasting more than 30 minutes. Symptoms of moderate traumatic brain injury are similar to those of mild traumatic brain injury but more serious and longer-lasting. Severe traumatic brain injury knocks you out for more than 24 hours. Symptoms of severe traumatic brain injury are also similar to those of mild traumatic brain injury but more serious and longer-lasting.
A long-term memory is anything you remember that happened more than a few minutes ago. Long-term memories can last for just a few days, or for many years. Long-term memories aren't all of equal strength. Stronger memories enable you to recall an event, procedure, or fact on demandâfor example, that Paris is the capital of France. Weaker memories often come to mind only through prompting or reminding.