(3~4) John and Sylvia were very rich and had many friends. They had a large and beautiful house full of expensive paintings. One day, they received two free theater tickets at first. However, when they could not find out who had sent them the tickets, they became confused and surprised. There was no letter in the envelope with the tickets. “They must forget to put a letter in,” John said. “How strange! We don’t know who to thank.” They phoned many of their friends and asked, “Did you send us theater tickets?” “No, we didn’t send them to you, ” their friends answered. Sylvia told her husband, “It is strange, but we shouldn’t waste the tickets. Everyone says that the play is very good.” And then, they just went to the theater.  But they did not really enjoy the play because they were worrying all the time. The play started at eight o’clock and finished at half past ten. When they got home, it was already eleven o’clock in the evening. There was a note on their front door. It said, “We hope you enjoyed the play.” When they opened their door, inside the house was not a single painting. They didn’t see anything but an empty house.  * receive收到 confused感到困惑的 empty空的 sent (send 的過去完成式)
1.What did John and Sylvia do after they phoned and asked their friends?