Alice was twenty-three years old, and she was a nurse at a big hospital . She was very kind and all of her patients   likes her very much . One day she was out shopping. She saw an old woman. The woman was waiting to cross   a busy street . Alice wanted to cross the street, too. So she went over to help the woman cross the street. When Alice was near her, she suddenly laughed  and said, " Mrs Green ! You were my patient in the hospital last year." Mrs Green was very happy to see her. "I will help you cross the street, Mrs Green," Alice said. "Oh, thank you very much , Alice , " Mrs Green said and stepped   forward  . "No, no, Mrs Green," Alice said quickly . "Wait! The light is still red." "Oh," Mrs Green answered when she stepped back. "I can easily cross the street by myself   when the light is green ." When did Mrs Green want to cross the street?
When the light was green. When the light was on. When the light was off. When the light was red.