This is a picture of a classroom. The classroom is big and clean. You can see a teacher's desk, five desks and six chairs. You can see a girl and a boy, too. Three books are on the teacher's desk. A pencil box is on the desk. Two pens and two rulers are in the pencil box. A schoolbag is under a chair. A ball is on the floor. The girl is Linda; she is 11. The boy is Mike, he is 12. They are in Class Two, Grade one. They are friends. Their teacher is Miss Green. She is not here. Mike and Linda are  _  .
teacher and student brother and sister cousins friends