词数:604阅读难度:建议阅读时间:7分钟Think about the people in your life who are 65 or older.Some of them are experiencing the usual mental difficulties of old age,like forgetfulness or a dwindling attention span.Yet others somehow manage to remain mentally sharp.My father-in-law,a retired doctor,is83 and he still edits books and runs several medical websites. Number of words: 604 Reading difficulty: Recommended reading time: 7 minutes Think about the people in your life who are 65 or older.Some of them are experiencing the usual mental difficulties of old age, like forgetfulness or a dwindling attention span.Yet others somehow manage to remain mentally sharp.My father-in-law, a retired doctor, is83 and he still edits books and runs several medical websites.