根据短文内容选择正确答案。
Smile（微笑）
Smile, how warm the world is!It can make anyone happy. It's not like anything else, but just warm, makes you feel warm.
Mother's smile is helpful（有帮助的）. When you are sad, it can make you happy again. When you fail（失败）to do something, it can make you stand up and work hard again. When you give up（放弃） doing something, it can make you try your best again.
Smile, so easy, and so useful. Everyone needs others' smile. When we give others a smile, we will feel happy, too. And maybe next time, when you need a smile, the others will give it to you. Let's learn to smile often, I think it can even make the whole world（整个世界）warm. Living with a smile, everyday will be sunshine.