[单项选择]粉尘是指（）。 A. 较长时间悬浮于空气中，直径＞0.1μm的固体颗粒 B. 较长时间悬浮于空气中，直径＞0.1mm的固体颗粒 C. 较长时间悬浮于空气中，直径＞1.0mm的固体颗粒 D. 较长时间悬浮于空气中，直径＞0.2μm的固体颗粒 E. 较长时间悬浮于空气中，直径＞0.2mm的固体颗粒
第7题: [单项选择]What is found to have close relationship with rapid increase in population A. War between 2 countries. B. Ways discovered to increase productivity. C. Migration from a continent to another continent. D. A new religion beginning to be accepted by peopl 参考答案:B 答案解析:[注释] 答案必须在通读全文之后通过对各细节的概括才能得知：每一次都与生产力和生产方式的提高有关。即第一次在第一段倒数第二句；第二次在第二段第一句；第三次在第三段第一句。
第13题: [单项选择]{{B}}Passage One
Questions 26 to 29 are based on the passage you have just heard.{{/B}} A. Growth of violence on TV. B. Decreasing of moral standards. C. Destructive threat from nuclear explosives. D. All of the above. 参考答案:D 答案解析:[听力原文]
What is the cause for this frightening developmet
