BMr Jackson has a happy family． His wife stopped working after they married．They have two children． One is a daughter，Susan，and the other is a son， Bill．Susan works in a famous university and Bill is a good policeman．' They are both married and they have their own fami- lies． And Mr Jackson became the manager of a company． He can get much money every year．But people find the man always look worried this month． And he-s much fatter than be- fore． Sometimes he-s out of breath when he goes up to his office on the second floor．He often complains that he can't sleep well in the night and eels tired． So his friends asked him to go to see a doctor．"Medicine can-t help you， Mr Jackson， the doctor said after he looked him over． "Do more exercise if you want to live longer． ""But what sport can I do?""Playing golf(失球)． It’ll be useful to you． "The man， of course， has to listen to the doctor． He goes to play golf on weekends． He enjoys himself there， but he can-t learn it well．One day the ball dropped on an anthill(蚁丘)． After many swings(挥动球杆） he demol- ished(毁坏) the anthill， but he still couldn't hit the ball． And only two ants were alive． Soone of them said to the other， "We'd better be on the ball if we don-t want to die!"( )26． Mr Jackson has___________ ．