题目内容：

语法填空

Happiness is like a pebble dropped into a pool to cause a circle of ripples. As Stevenson said, "Being happy is a duty."

There is no exact 1.  (definite) of the word "happiness". Happy people are happy for all sorts of reasons. The key is not wealth or physical well-being  2. we find beggars, the disabled and so-called failures 3. are extremely happy.

Being happy is a sort of unexpected dividend(红利). But staying happy is an accomplishment, a triumph of the soul. It is not selfish to strive 4.  it. It is, indeed, a duty to ourselves and 5. .

Being  6. is like an infectious disease. It causes people to shrink away from the sufferer. He soon finds himself alone and miserable. There is,  7. , a cure so simple that it seems, at first glance, ridiculous: if you don’t feel happy, pretend  8.  (be)!

It works. Before long you 9.  (find) that instead of annoying people, you attract them. You discover how deeply rewarding it is to be the center of a wider and wider circle of good will.

Then the make-believe becomes 10.  reality. You possess the secret of peace of mind, and can forget yourself in being of service to others.