Henry is from the USA. He is on holiday in London. One day he is not feeling very well. So he asks a waiter in the hotel, "I want to see a doctor. Can you give me the name of a good one?" The waiter looks in a book, and says, "Dr. Green." "Is he expensive?" "Well," the waiter answers, "Usually, you need to pay 20 pounds for the first time, and 15 pounds for later visit." Henry wants to save 5 pounds. When he goes to see the doctor, he says, "I've come again, doctor." For a few seconds, the doctor looks at his face carefully without say anything. Then he says, "Oh, yes." He examines Henry and says, "Everything's going fine. Just don't stop the medicine  I gave you last time." He wants to see a good doctor because   _  .
he is feeling bad he can save 5 pounds he wants to take some medicine home a good doctor is very expensive