A、They didn’t hear the instructions as it was noisy. B、They have no basic medical knowledge. C、They didn’t listen to the doctor

In her early days as an emergency room physician, Doctor Joanna Myer treated a child who had suffered a second degree burn.(19)After the child had been treated and was being prepared for discharge, Doctor Myer talked to the parents about how they should care for the child at home. Also listening to her were a half a dozen other family members. A few hours later, when she came to say goodbye, the family asked her to settle an argument they’d been having over exactly what advice she had given. "As I talked to them, I was amazed. " she said, "All of them had heard the simple instructions I have given just a few hours before, but they have three or four different versions. The most basic details were unclear and confusing. I was surprised, because these were intelligent people. " This episode gave Doctor Myer her first clue to something every doctor learns sooner or later—(20)most people just don’t listen very well. Nowadays, she says she repeats her instructions, and even conducts a reality check with some patients. She asks them to tell her what they think they are supposed to do. She also provides take-home sheets which are computer printouts tailored to the patients’ situation. Doc. Myer’s listeners are not unusual.(21)When new or difficult material is presented, almost all listeners are faced with the challenge because human speech lacks the stability and permanence of the printed word. Oral communication is fast-moving and impermanent.
Questions 19 to 21 are based on the passage you have just heard.
19. What do we know about the burned child from the passage?
20. Why didn’t the child’s family members understand the instructions?
21. Why is it hard for listeners to understand new and difficult material?