单词：alluvial cone sand trap
单词：alluvial cone sand trap 相关文章
This is Scientific American's 60-Second Science. I'm Steve Mursky. Got a minute? Orbiting around stars far far away is sand. Astronomers have found sandy particles circling a pair of stars about 2,400 light years from us. And they think they might be
Scientific American(三)月
Better known for its diamond fields, gold exploration and mining in Sierra Leone is on the increase. The British company, Cluff Gold, has announced it will build a mechanized gold mine in the southern Kangari hills after finding large deposits of gol
VOA标准英语2010年(四)月
Glass is made chiefly of fine white sand or silica melted in a furnace. To make the sand melt easily, we must mix with it some soda, some chalk or lime, and a small quantity of broken glass. 玻璃主要由细致的白沙或硅石在熔炉中炼成。为
英国学生科学读本
They may be a little safer here. But the food in the forest is far less nutritious than on the riverbanks. If they want to eat well and avoid wolves this winter, they'll need to keep on moving. As the elk move gradually downwards, they follow the riv
自然百科2012年
By Naomi Schwarz Dakar 04 December 2007 Diamonds from Sierra Leone have fueled the country's gruesome civil war and enriched warlords. Now, the government and activists are trying to make sure the profits from Sierra Leone's post-conflict diamonds he
VOA常速英语2007年（十二月）