Inclusion Criteria:  College students from all over the country, over 17 years old, have a physical examination before entering school Sign the informed consent form, voluntarily participate and fill in the questionnaire  Exclusion Criteria:  People with diabetes, hyperthyroidism or hypothyroidism, peptic ulcer, inflammatory bowel disease, digestive tract tumor or severe medical and surgical disease History of abdominal surgery (such as esophagus, stomach, small intestine, colon, rectum, appendix, gallbladder, hysterectomy, cesarean section) Recently, there are some alarm symptoms, such as relieving black stool, bloody stool, hematemesis, abnormal anemia, fever, abnormal weight loss (no intention to lose weight, weight loss 5 kg in 3 months), change of defecation habits, dysphagia and so on In the past 4 weeks, he has taken drugs that affect the judgment of gastrointestinal symptoms, such as anti-inflammatory painkillers, diazepam drugs, anti-anxiety drugs, depressants and so on