【正确答案】正确答案：A variety of explanations have been put forward for the apparent decline in adults: physical factors such as the loss of "plasticity" in the brain and "lateralization" of the brain; social factors such as the different situations and relationships that children encounter compared to adults; cognitive factors such as the interference with natural language learning by the adult's more abstract mode of thinking; and input factors that adults spend only a few hours each week of school time, rather than via the constant interaction experienced by a child, with a lot of other occupations.