hospitals receive more patients suffering acute respiratory and heart diseases.烟雾引起PM 2.5指数的增加，患病的人增多，因而医院的病人增多，人们的收入的增加并不是由于烟雾的影响。

　　2．To make China stronger we have to develop economy, but ________.

　　A．we have to sacrifice air as the price

　　B．the dirty air is not what we want

　　C．ecological progress can be ignored

　　D．the smog is the only by­product

　　解析：B　细节理解题。根据最后一段第一句What the public wants is a strong and beautiful China.我们为了使中国变得更加强大而发展经济，但是不能牺牲我们的空气质量。

　　3．The underlined word "they" in Paragraph 6 refers to ________.

　　A．human beings

　　B．other plants

　　C．space technologies

　　D．industrial development

　　解析：A　词义猜测题。根据该句中的so that one day all human beings can migrate to the red planet because they have destroyed Earth.这里用代词代替前面出现的human beings。

　　4．From the last two paragraphs we can infer that ________.

　　A．high­tech can completely solve the problem of pollution

　　B．space technologies should be developed in a large scale

　　C．we can move to the Mars after the Earth has been destroyed

　　D．we must protect the environment while developing economy

解析：D　推理判断题。根据最后一句The words have shown the central