1.你应该微笑面对人生.（smile at) You should smile at the life.
2.请每天保持微笑.（keep） Please keep smiling every day.
3.这个婴儿笑的很开心（happy) The baby smiles happily.
4.小女孩离开前给了妈妈一个微笑.（before）The little girl gave her mother a smile before leaving.