题目内容：

    Picture an iceberg(冰山).You'll probably imagine something white as snow rising up out of a blue sea. But icebergs can be all sorts of shades. They can be from a frosty blue to an attractive green.

Researchers and sailors have observed emerald(翠绿色)icebergs for years. A large piece of ice "mast-high" and "green as emerald" even appears in Samuel Taylor Coleridge's 1834 poem. But they haven't found out exactly why these icebergs look the way they do.

A new paper led by Stephen Warren was published. It all has to do with what icebergs are made out of. Icebergs break off glaciers(冰川)or ice shelves, which happens mainly around Antarctica and Greenland. They begin their lives as snowfall that accumulates over time. So. icebergs contain air pockets with the form of bubbles that spread light. With some exceptions and rare lines, glacier ice tends to look bluish white.

At first，Warren guessed that the green was a product of melt carbon. And it came from rotting plants or sea animals. But samples(样本)didn't prove it. Another idea started to take shape after they had found a high concentration of iron in a sample of sea ice from the Amery Ice Shelf.

When glaciers rub across land, they produce what's known as glacier flour. It is a product of bedrock being ground clown by the moving mass. As glaciers move away, these remains are usually washed out into water. in particles sometimes too small to be noticeable to your eyes. But on land. soil and rocks contain iron oxides that often have rosy colors. like reds, yellows, and browns-and since the sea ice contained 500 times more iron than the glacier ice, Warren wondered whether the remains were responsible for icebergs taking on a green appearance.

He doesn't know for sure. He's hoping to secure money so that he can return to the area and study the icebergs themselves.

1.Why is Samuel Taylor Coleridge's poem mentioned in the text?

A. It tells why icebergs look the way they do.

B. It describes vividly what icebergs are like.

C. It says causes of the appearance of icebergs.

D. It proves the existence of colorful icebergs.

2.What can we know about Stephen Warren's paper?

A. It draws on researchers' and sailors' views.

B. It is the record of the movement of icebergs.

C. It talks about how icebergs come into being.

D. It is a collection of various social phenomena.

3.What does the underlined word "it" in paragraph 4 refer to?

A. A sample of sea ice. B. Warren's first guess.

C. Warren's idea on iron. D. A product of melt carbon.

4.What is paragraph 5 mainly about?

A. The possible reason why icebergs look green.

B. Where most of icebergs eventually disappear.

C. How icebergs take in the colors from glaciers.

D. The way in which icebergs breaks off glaciers.