The building is topped by a ventilated roof with a metal sheetcovering.
建筑物上的可通风屋顶是由金属片覆盖的。
2
The ice, much of it tens of thousands of years old, originates in the 660, 000-square-mile ice sheetcovering 80 percent of Greenland.
我们所见的冰，大部分有着上万年的历史，都发源于覆盖格陵兰岛80%面积的66万平方英里冰原。
3
The way further south into the rest of America was through an ice-free corridor between the Rocky Mountains on the Pacific side, and the vast continental ice-sheetcovering Canada on the other.