A passenger（乘客）told an air hostess that he needed a cup of water to take his medicine when the plane just took off. She said to him that she would bring him the water in ten minutes.
The air hostess was kept so busy that she forgot to give him the water. As a result, the passenger was held up to take his medicine. Thirty minutes later, when the passenger’s ring for service sounded, the air hostess hurried over to him with a cup of water, but he refused it.
In the following hours on the plane, each time the air hostess passed the passenger, she would ask him with a smile whether he needed help or not. But the passenger never replied to her.
       When the passenger was going to get off the plane, he asked the air hostess to hand him the passenger’s booklet. She knew that he would write down sharp words about her job, but with a smile she handed it to him.
Off the plane, the air hostess opened the booklet, and smiled because the passenger wrote, “On the flight, you asked me whether I needed help or not for twelve times in all. How can I refuse your twelve sincere smiles?”

—Lucy.She sings ________ her sister.