20. For the elderly, it is never too late to start physical exercise.
(A) Many studies have shown that elderly persons benefit from a variety of exercise programs.
(B) There is evidence proving that continued exercise reduces the degree of physical andmental slowness.
(C) Before starting exercise programs, the elderly should have a physical examination toensure they choose the right kind of exercise.
(D) Caring for grandchildren is a good way to help the elders stay mentally active.