Remiazolam vs Propofol Total Intravenous Anesthesia on Postoperative Neurodevelopment After General Anesthesia in Children

The goal of this clinical trial is to learn the effects of remimazolam for total intravenous anesthesia on the neurodevelopment of children aged 3-6 years who underwent tonsil/adenoid removal surgery after general anesthesia when compared with propofol. It will also learn about the safety of remimazolam used for children. The main questions it aims to answer are: * Does remimazolam improve the postoperative neurodevelopmental outcomes of the children after general anesthesia compared with propofol? * What medical problems do participants have when receive remimazolam for general anesthesia? Researchers will compare remimazolam to propofol to see if remimazolam improve the postoperative neurodevelopmental outcomes of the children after general anesthesia. Participants will: * Receive remimazolam or propofol for general anesthesia induction and maintenance * At 1-3 years after the surgery, the Wechsler Preschool and Primary Scale of Intelligence - Fourth Edition was used for face-to-face assessment of the children's neurodevelopmental status. * Use scales such as BRIEF-P and CBCL to conduct face-to-face assessments of the patient's cognitive functions in other areas.