A passenger told an air hostess that he needed a cup of water to take his medicine when the plane just took off. She told him that she would bring him the water in ten minutes.

Thirty minutes later, when the passenger's ring for service sounded, the air hostess flew in a flurry. She was kept so busy that she forgot to deliver him the water. As a result, the passenger was held up to take his medicine. She hurried over to him with a cup of water, but he refused it.

In the following hours on the flight, each time the stewardess passed be the passenger she would ask him with a smile whether he needed help or not. But the passenger never paid heed to（注意） her.

When he was going to get off the plane, the passenger asked the stewardess to hand him the passengers' booklet. She was very sad. She knew that he would write down sharp words, but with a smile she handed it to him. 

Off the plane, she opened the booklet, and cracked a smile（展颜微笑）, for the passenger put it, "On the flight, you asked me whether I need help or not for twelve times in all. How can I refuse your twelve sincere smiles?"

That's right! Who can refuse your twelve sincere smiles from a person?