英語聽力：冰河綠洲-2

By piecing together the evidence these creatures left behind, we can build a picture of this sub-tropical corner of the continent as it was 13,000 years ago. While most of North America was still in the grip of the Big Freeze, Florida was an ice age oasis. Florida is aptly named the Sunshine State. With an average of eight hours of sun a day, it seems a world away from any ice age. Even 13,000 years ago, the massive ice sheets were hundreds of miles away to the north. So what was it like back then?

To investigate Florida's ice age past, one of the best places to look is under ground and up the water. Just below the surface lies a very strange world. Millions of years of water action has dissolved the limestone rock, forming a system of flooded caves and tunnels. This vast underground network runs for thousands of miles. Much of Florida is basically a big rock honeycomb. In places the water is forced to the surface, forming springs. Florida has one of the largest concentrations of springs in the world. Filtered through sand and rock, the water is crystal-clear. And welling up from deep within the earth, it is a constant 22 degrees centigrade.

1 oasis

n.(沙漠中的)綠洲，宜人的地方

參考例句：

They stopped for the night at an oasis.他們在沙漠中的綠洲停下來過夜。

The town was an oasis of prosperity in a desert of poverty.該鎮(zhèn)是貧窮荒漠中的一塊繁榮的“綠洲”。

2 massive

adj.巨大的，大規(guī)模的，大量的，大范圍的

參考例句：

A massive sea search has failed to find any survivors.經(jīng)過大規(guī)模的海上搜救仍未找到幸存者。

He drank a massive amount of alcohol.他喝了大量的烈酒。

3 limestone

n.石灰石

參考例句：

Limestone is often used in building construction.石灰?guī)r常用于建筑。

Cement is made from limestone.水泥是由石灰石制成的。