Bev could not do her work.She felt too tired.She put down her book,yawned(打哈欠) and felt better.Bev looked up.Had the teacher seen her? To her surprise,the teacher yawned,too.He took a long breath (呼吸) and opened his mouth wide.He closed his eyes a bit and let out his breath in a big,slow yawn.Then Bev heard other yawns.The teacher said,“Bev yawned because our doors and windows are closed.And the room is warm,her body needed more air.Maybe she yawned because she was tired.Maybe she was hungry.Or she just needed to move a bit.Do you feel better now,Bev?” he asked.“Yes,” said Bev.“Yawns wake us up,” the teacher said.“When you yawn,you stretch(伸展) many parts of your body.That stretching makes you feel good.” There were more yawns.“People do not know why they yawn,” the teacher said.“But if you see or hear a yawn,you may yawn too.And once your yawn starts,you can't stop it.You may close your mouth to stop it.But the yawn will still come.” The teacher stood up and said,“Let's open the window and let some air in.You may also go out for a drink.Having a cold drink or washing your face help to stop yawns.Bev may go first.”
How do you feel now after you have read this story? Did you yawn? Watch a friend read this.See if your friend starts to yawn.If you see a yawn,you will know why!