填空题 A physically and mentally active
B be alert and receptive
C engage in mental, activities
D the benefits of challenging the brain
E beneficial and happy
F maintain mental alertness

填空题 If people are faced with information that gets them to think about things they are interested in, they will be_______.
填空题 Many experts are putting the theory to work in their own lives because they are convinced of_______.
填空题 Such specific training as learning to memorize enormous amounts of information is of less interest than being able to_______.
填空题 Older people need to keep both_______.