单项选择题


In this section, you will hear several news items. Listen to them carefully and then answer the questions that follow.
Questions 21 to 23 are based on the following news. At the end of the news item, you will be given 15 seconds to answer the questions.
Now, listen to the news.

How many people have been infected by bird flu in Hong Kong in 1997

A.At least three.
B.Six.
C.Thirteen.
D.Fifteen.