Questions 18 to 20 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now, listen to the passage. According to the talk, how has the island changed in the 20th century
A.The patterns of marriage have changed. B.Many deaf people have regained their hearing. C.Most of the original population has left the island. D.The island has become famous for its research facilities.