听力原文：

Scientists all over the world study the weather. They collect information about rain, wind, cloud and air temperature. But scientists can’t be everywhere, so sometimes they use other people, such as students, to help them. Students in many countries collect information about the weather. They do this to learn more about science. Every day, they measure the temperature of the air and the speed and the direction of the wind. They also measure how much cloud there is and how many centimeters of rain have fallen. When they finish these tests, the students send their information by e-mail to scientists. Scientists use this information to understand the world’s weather better.  

参考答案：4. B