In recent years, people pay more and more attention to floating dust, sand blowing and sandstorm weather. According to reports, in mid-April 2002, in the four major sandstorm centers in the world,

Question 30 examines the ability of candidates to make simple inferences from given information. The process of reasoning and judgment must be based on the grasp of the content and spatial position of the basic knowledge of world geography, that is, the topic tests the proficiency and application ability of candidates on the basic language of geography.

3 1 question examines candidates' understanding of the formation of rainfall processes in different regions under the background of atmospheric circulation. If the judgment in question 30 is correct, then, first of all, it can be judged that the sand-laden airflow cannot be an east-west airflow, that is, item C is not optional. At the same time, according to the geographical location and atmospheric circulation background of Switzerland, item A can also be excluded. The principle of rainfall formation tells us that the "sinking" of airflow mentioned in item D is also incorrect.

Question 32 reminds the society to pay attention to the harmfulness of the expansion of bare land area in big cities in the north while evaluating relevant knowledge. Master and understand the basic meteorological knowledge and principles, that is, options A and D can be excluded, and the sand source in general sand blowing weather should not be too far away.