[单项选择]Sulphur has occasionally been found in the earth in an almost pure state.
A. regularly
B. accidentally C. sometimes
C. successfully

[单项选择]For more than 40 years, Earth has been sending out distress signals. At first they were subtle, like the thin shells of bald-eagle eggs that cracked because they were laced (使混合) with DDT. Then the signs were unmistakable, like the covering of smoke over the Amazon rain forest, where farmers and ranchers (牧场主人) set fire to clear land. Finally, as the new millennium drew near, it was obvious that Earth’s pain had become humanity’s pain. The collapse of the North Atlantic cod (鳕鱼) fishery put 30,000 Canadians out of work and ruined the economies of 700 communities. In 1998, deforestation worsened China’s floods, which killed 3,600 people and left 14 million homeless. Population pressures and overcrowding raised the toll from 1999’s rains in Latin America, which killed more than 30,000 people and created armies of environmental refugees.
And how have we responded to four decades of ever louder distress signals We’ve staged a procession, of Earth Days, formed Green parties, passed env
A. Even though people around the world have taken various measures to save the earth, many ecosystems still keep declining.
B. As our world evolves, the relationship between Earth and humanity becomes closer and closer.
C. It’s essential and important to carry out a thorough research on the current state of the whole earth.
D. The continuous deterioration of the global environment has awakened most human beings to the importance of environmental protection.

[填空题]
An earth scientist has rejigged the periodic table to make chemistry simpler to teach to students.
(1) But Bruce Railsback from the University of Georgia says he is the first to create a table that breaks with tradition and shows the ions of each element rather than just the elements themselves.
"I got tired of breaking my arms trying to explain the periodic table to earth students, " he says, criss-crossing his hands in the air and pointing to different bits of a traditional table.
(2) But he has added contour lines to charge density, helping to explain which ions react with which.
"Geochemists just want an intuitive sense of what’s going on with the elements, " says Albert Galy from the University of Cambridge, (3)
(4) He explains that sulphur, for example, shows up in three different spots — one for sulphide, which is found in mineral

[填空题]
An earth scientist has rejigged the periodic table to make chemistry simpler to teach to students.
(46) But Bruce Railsback from the University of Georgia says he is the first to create a table that breaks with tradition and shows the ions of each element rather than just the elements themselves.
"I got tired of breaking my arms trying to explain the periodic table to earth students," he says, criss-crossing his hands in the air and pointing to different bits of a traditional table. (47) But he has added contour lines to charge density, helping to explain which ions react with which.
"Geochemists just want an intuitive sense of what’s going on with the elements," says Albert Galy from the University of Cambridge (48)
(49) He explains that sulphur, for example, shows up in three different spots one-for sulphide, which is found in minerals, one for sulphite, and o