Question 20 is based on the passage you have just heard.

听力原文

        (19) [Sunshine and high temperatures can mean picnics and parks and trips to beaches, but they can make your body react in some strange ways.] First, sunshine can actually affect your breath. You may think that summer is the perfect time to go on a date or chat with an attractive boy or girl, (20) [but excessive heat can cause you to lose water, which has been proven to have a pretty unattractive side effect—bad breath.] When you are lacking water, your mouth becomes dry. Bacteria accumulates because there isn’t enough water in your mouth to wash it away. Sunshine can stop you from sweating too. The body’s normal temperature is 36 to 37℃, but if it heats up to 40 to 41 degrees, you may find yourself getting heat stroke. At that point, your heat regulatory system can essentially quit, which stops you from sweating as your body tries to keep water around your vital organs. (21) [However, the sun can have a positive influence on your body by raising your energy levels. You might feel like the sun is giving you extra energy for your day, which is actually happening.] And vitamin D from sunshine can help your body to absorb certain minerals, which are linked to building stronger bones. Therefore, I suggest you spend more time in the park with your friends, but make sure you apply lots of skin protection, and fill up those water bottles too.

20. What does the passage say is a negative side effect of water loss?（根据文章所说，水分流失会导致什么不好的副作用？）

解析：A。录音前半部分提到，过热的天气会导致体内水分流失，从而产生一个非常讨厌的副作用——口臭（bad breath）。A项与此一致，故为正确答案。

错项排除：录音中提到，天气过热会阻止身体出汗，B项与此相悖，故排除。C项Breathing difficulty和D项High blood pressure在录音中无依据，故均可排除。