Running a marathon (马拉松)
Have you ever taken part in a marathon? A marathon is 42km long. It is the longest race in the world. To make the runner’s body work, harder training is quite necessary. A runner should start to prepare for a marathon at least three months before. Preparation may have races, many hours of running at different speeds and changes in diet(饮食). During the training time the runner must eat a fit diet.  The diet should have lots of things needed in training the players.
In the early days of training, runners run 80km per week. The running is increased every two or three weeks and at least two long runs per week are needed.
Two weeks before the marathon, the training programme becomes less, from 100km per week down to 60km and then to 30km in the final week. On the last two days they may not run at all.
Breakfast should be eaten at least three hours before the race.  Easily digested(消化) food such as cereal(麦), toast(烤面包) and scrambled(捣碎) egg is best,  with as much fluid(液体) as possible.  Runners should drink water about half an hour before the race to keep up the body fluid. 
【小题1】According to the passage, when should a marathon runner begin his training?

Imagine there is a bank that puts $ 86, 400 in your account ( 账户)each morning. It carries over no balance from day to day. Every evening the bank writes off( 注销)the balance that you failed to use during the day. What would you do? Take out every cent,  of course \
Each of us has such a bank. Its name is TIME. Every morning,  it puts in 86, 400 seconds. Every evening it writes off,  as it is lost. There is no balance or overdraft 透支) . If you fail to use the day’s savings,  the lost is yours. There is no going back. There is no taking from " tomorrow". You must make good use of it so as to get more in health,  happiness and success!
The clock is running. Make the most of today. To realize the value of ONE YEAR,  ask a student who failed a grade; To realize the value of ONE MONTH,  ask a mother who gave birth to a premature( 早产)baby; To realize the value of ONE WEEK,  ask the editor of a weekly newspaper; To realize the value of ONE HOUR,  ask the lovers who are waiting to meet; To realize the value of ONE MINUTE,  ask a person who missed the train; To realize the value of ONE SECOND,  ask a person who just avoided(避免)an accident.
Make good use of every moment that you have. Remember that time waits for no one. Yesterday is history. Tomorrow is a mystery. Today is a gift. That’s why it’s called "The Present".
【小题1】The underlined word "balance" in paragraph 1 means_________.