单项选择题


In this section, you will hear several passages. Listen to the passages carefully and then answer the questions that follow.
Questions 11 to 14 are based on the following passage. At the end of the passage, you will be given 20 seconds to answer the questions. Now, listen to the passage.
All of the following are causes of being bitten by mosquitoes EXCEPT______.

A.carbon dioxide and other odors
B.sweat
C.the quality of your skin
D.heart and blood pressure medicine