题目

在下列溶液中，各组离子一定能够大量共存的是A．使酚酞试液变红的溶液：Na+、Cl-、SO42-、Fe3+B．使紫色石蕊试液变红的溶液：Fe2+、Mg2+、NO3-、Cl-C． c(H+)=10-12 mol·L-1的溶液：K+、Ba2+、Cl-  、Br-D．碳酸氢钠溶液：K+、SO42-、Cl-、H+  答案：C解析:本题考查离子共存。在溶液中离子之间若能发生反应，则就不能大量共存，否则就能大量共存。使酚酞试液变红的溶液应该显碱性，在碱性溶液中Fe3+不能大量共存，A不正确。使紫色石蕊试液变红的溶液应该显酸性，在酸性溶液中NO3－能氧化Fe2+，B不正确；c(H+)=10-12 mol·L-1的溶液，说明溶液显碱性阅读理解 　　Something big is happening to the human race-something that could be called The Great Transformation. 　　The Transformation consists of all the changes that are occurring in human life due to advancing technology. For thousands of years such progress occurred slowly. Now, everything is changing so fast that you may find yourself wondering where all this progress is really leading. 　　Nobody knows what all these changes really will mean in the long run. But this mysterious Transformation is the biggest story of all time. It is the story of the human race itself. 　　Some people worry about what will happen when the deposits of petroleum are gone, but already researchers are finding all kinds of new ways to obtain energy. Someday, solar power collected by satellites circling the earth or fission power manufactured by mankind may give us all the energy we need for an expanding civilization. Space exploration promises to open up many new territories for human settlement, as well as leading to the harvest of mineral resources like the asteroids. 　　Scientific research continues to open up previously undreamed of possibilities. Fifty years ago, few people could even imagine things like computers, lasers, and holography. Today, a host of newly emerging technologies such as artificial intelligence and genetic engineering are opening up all kinds of new paths for technologists. 　　Like it or not, our advancing technology has made us masters of the earth. We not only dominate all the other animals, but we are reshaping the world’s plant life and even its soil and rocks, its waters and surrounding air. Mountains are being dug up to provide minerals and stone for buildings. The very ground under our feet is washing ways as we chop down the forests, plow up the fields, and excavate foundations for our buildings. 　　Human junk is cluttering up not only the land but even the bottom of the sea. And so many chemicals are being released into the air by human activities that scientists worry that the entire globe may warm, causing the polar icecaps (冰冠) to melt and ocean waters to flood vast areas of the land. During the twentieth century, advancing technology has enabled man to reach thousands of feet into the ocean depths and to climb the highest mountain. Mount Everest, the highest mountain of all, resisted all climbers until the 1950s. Now man is reaching beyond Earth to the moon, Mars, and the stars. 　　No one knows what the Great Transformation means or where it will ultimately lead. But one thing is sure: Human life 50 years from now will be very different from what it is today. It’s also worth nothing that our wondrous technology is posing an increasingly insistent question: When we can do so many things, how can we possibly decide what we really should do? When humans were relatively powerless, they didn’t have to make the choices they have to make today. 　　Technology gives us the power to build a magnificent new civilization－if we can just agree on what we want it to be. But today, there is little global agreement on goals and how we should achieve them. So it remains to be seen what will happen as a result of our technology. Pessimists worry that we will use the technology eventually to blow ourselves up. But they have been saying that for decades, and so far we have escaped. Whether we will continue to do so remains unknown－but we can continue to hope. 1．The Great Transformation is caused by ________. [　　] A．artificial intelligence and genetic engineering B．the shortage, of natural resources C．the development of practical science D．unknown reasons 2．Today it is impossible for people to build a remarkable new civilization because ________. [　　] A．nobody is optimistic about the future B．human beings are unable to do so C．people disagree with each other in many ways D．people are not interested in it 3．The more chemicals we send into the air, the less land we will possibly have because ________. [　　] A．chemicals will wash away fields B．water levels will go up C．more and more land will be covered by ice D．none of the above 4．________ after all the petroleum is used up. [　　] A．We can depend on solar power or fission for energy B．We can ask God for help C．We will have no source to obtain energy D．We can bum wood