单项选择题


Questions 11 to 13 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.

Here are no black rats in Europe today because ______.

A.they got plague in the Middle Ages
B.they live in America, Asia and Africa now
C.men killed them all with diseases
D.brown rats took their place