5. Yellowstone is an ideal home of many different species of animals.

Sleeping Giant

Right now, an eruption' is brewing (酝酿) in Yellowstone National Park (黄石国家公园)．Sometime during the next two hours, the park’s most famous geyser(间歇泉), Old Faithful, will begin gurgling(汩汩而流)boiling water and steam._____ (1)

Old Faithful is not only a spectacular sight; it's also a constant reminder that Yellow-stone sits on one of the largest volcanoes in the world．If you have never heard of Yellow-stone's volcano, you are not alone._____ (2) Yet it has erupted three times during the last 2 million years．And one of those eruptions spewed(喷泉 )enough volcanic ash and other debris to blanket half the United States.

Yellowstone’s volcano is sometimes called a “supervolcano”, or extremely large and explosive calderas(破火山口 )volcano._____ (3)．This supervolcano formed over a hot spot, an extremely hot area in Earth's mantle(地幔)．John Valley, a volcano professor,said that as the crust moves across a hot spot, the hot spot melts a section of the plate moving over it, forming "one volcano after another".

The Yellowstone hot spot melts thick continental (大陆的)crust, which may cause

catastrophic(灾难性的)eruptions．According to experts, the eruptions that created each of the three calderas in and around Yellowstone National Park were larger than any other volcanic eruption in recorded history．The most recent eruption, which happened 640,000years ago, produced at least 1,000 cubic kilometers of ash and debris and blanketed most of the western half of the United States．_____(4)

(Geological evidence shows Yellowstone has blown its stack every 700,000 years or so.“If nalure were truly that regular and reliable, we would be due for another eruption soon,” said Valley．“However, these processes are subject to variability(可变性), so we don’t really know when the next eruption will happen．”

_____ (5) It is the volcanic energy that powers the geysers and hot springs, creates

the mountains and canyons(峡谷-), and generates the unique ecosystems that support Yellowstone's diverse wildlife.

A．Three calderas make up more than a third of Yellowstone National Park.

B．The first Yellowstone eruption, 2 million years ago, released more than double that amount of ash and debris.

C．The volcano is so inconspicuous(不显眼J)that few .people know it exists.

D．Then, an enormous fountain will shoot high into the air.

E．While the active geologist processes at Yellowstone do pose some risk to the public, they also make it a unique treasure．

F．Yellowstone National Park attracts the interest of geologists the world over.

第 46 题

请选择（1）处的最佳答案．

The famous Yellowstone National Park is situated in northwestern part of

A．California.

B．Arizona.

C．Wyoming.

D．Massachusetts.

Why is Yellowstone National Park important？()

A、Because it is the first national park in the world.

B、Because it is in America.

C、Because it is the biggest national park in America.

D、Because it is the first national park in America.

此题为判断题(对，错)。

根据下面短文内容，回答题。

Sleeping Giant

第1题___________ 查看材料

A.Three calderas make up more than a third of Yellowstone National Park.

B.The first Yellowstone eruption，2 million years ago， released more than double that amount of ash and debris.

C.The volcano is so inconspicuous （不显眼的 ） that few people know it exists.

D.Then， an enormous fountain will shoot high into the air.

E.While the active geological processes at Yellowstone do pose some risk to the public， they also make it a unique treasure.

F.Yellowstone National Park attracts the interest of geologists the world over.

A、Yellowstone National Park

B、The Grand Canyon

C、Niagara Falls

D、The Great Salt Lake