In a book called Magnificent Obsession, by Lloyd C. Douglas, a description is given of people helping others but doing it secretly. When difficult problems worried a person, friends nearby would meet to discuss possible solution without the person knowing their actions. When a solution was agreed upon, one or two of the friends would carry out the plan and solve the problem secretly, to the great delight of the worried person. The helpers would stand by privately, content with their success. No reward was given to the problem solvers, not even a sincere “thank you”, because they were never known.
This idea is popular today but in a different way. The phrase “pay it forward” is now used when one person helps another. However, the person helped may not be able to repay the person or group that helped them. So rather than return the favor to their helpers, they are supposed to help someone else in the future, which means they pay it forward. It is a sense of responsibility(责任) which makes us want to give back in equal measure to the one who has helped us. But, in this case, the responsibility turns to helping someone in the future.
Suppose your elderly grandmother pays part of your schooling. She may tell you there is no need to repay her because it is a gift from someone who loves you very much. Nothing would please her more than to have you use her money to get a good education.
You may never be able to repay her for such a gift. However, she not only gave you some money, but she provided you with an example that you should also help other people who need it.
People with serious needs are everywhere. Many are children who need better clothes, more books and even better schools. Some are elderly people who can't afford their medicine or a doctor's care. Consider how you can “pay it forward”rather than pay money back to your grandmother.
为前n 
，摆a个正方形用