Jack is a twenty-year-old young man. Two years ago, when he finished middle school, he found work in a shop. Usually he works until ten o'clock in the evening. He is very tired when he gets home. After a quick supper he goes to bed and soon falls asleep. His grandma who lives downstairs is satisfied with   him. One day, on his way home, he met Mary. They were both happy. He asked the girl to his house, she agreed happily. He bought some fruit and drinks for her. And they talked about their school, teachers, classmates and their future  . They talked for a long time. "Have a look at your watch, please," said the girl. "What time is it now?" "Sorry, something is wrong with my watch," said Jack. "Where's yours?" "I left it at home." Jack thought for a moment and found a way. He began to stamp his foot on the floor, "Bang! Bang! Bang!" The sound woke his grandma up. The old woman shouted downstairs, "It's twelve o'clock in the night, Jack. Why are you still jumping upstairs?" ,. From the story, we can know that Mary is Jack's  _  .
classmate colleague aunt wife