填空题 A Running 10 miles every day
B It does not exist
C They hope to find out what has made them live so long
D walking
E enjoy life
F It will be very expensive

填空题 Most people will not be able to use the new technology because ______.

填空题 Some scientists are studying people who live a long time because ______.

填空题 According to the passage, the healthiest exercise is ______.

填空题 People who live into very old age always ______.