[单项选择]

Volcanoes

There are thousands of volcanoes (火山) all over the world. What makes volcanoes What happens
The inside of the earth is very hot. Because it is very, very hot, the rock has melted like ice. It has become liquid, like water. It is always boiling, like water in a kettle. If you have seen a kettle boiling, you know that the steam and boiling water try to get out. The very hot melted rock inside the earth also tries to get out. Usually it cannot because the outside of the earth is too thick and strong.
But in some places the outside of the earth is thin and weak. Sometimes a crack appears. The hot melted rock, which we call "lava" (熔岩), pushes out through the crack and bursts through. Steam and gas shoot up into the air and the hot melted lava pours out. Big pieces of rock may be thrown high into the air.
After a while the volcano becomes quiet again. The melted lava becomes hard. Later
A. boiling water
B. boiled water
C. melted rock
D. melted ice

[单项选择]

There are thousands of volcanoes (火山) all over the world. What makes volcanoes What happens
The inside of the earth is very hot. Because it is very, very hot, the rock has melted like ice. It has become liquid, like water. It is always boiling, like water in a kettle. If you have seen a kettle boiling, you know that the steam and boiling water try to get out. The very hot melted rock inside the earth also tries to get out. Usually it cannot because the outside of the earth is too thick and strong.
But in some places the outside of the earth is thin and weak. Sometimes a crack appears. The hot melted rock, which we call "lava" (熔岩), pushes out through the crack and bursts through. Steam and gas shoot up into the air and the hot melted lava pours out. Big pieces of rock may be thrown high into the air.
After a while the volcano becomes quiet again. The melted lava becomes hard. Later
A. a crack in the earth
B. a mountain by the sea
C. a big fire
D. steam and gas

[单项选择]
There are thousands of volcanoes (火山) all over the world. What makes volcanoes What happens
The inside of the earth is very hot. Because it is very, very hot, the rock has melted like ice. It has become liquid, like water. It is always boiling, like water in a kettle. If you have seen a kettle boiling, you know that the steam and boiling water try to get out. The very hot melted rock inside the earth also tries to get out. Usually it cannot because the outside of the earth is too thick and strong.
But in some places the outside of the earth is thin and weak. Sometimes a crack appears. The hot melted rock, which we call "lava" (熔岩), pushes out through the crack and bursts through. Steam and gas shoot up into the air and the hot melted lava pours out. Big pieces of rock may be thrown high into the air.
After a while the volcano becomes quiet again. The melted lava becomes hard. Later the same thing happens again and
A. liquid
B. water
C. smoke
D. hard

[单项选择]

There are thousands of volcanoes (火山) all over the world. What makes volcanoes What happens
The inside of the earth is very hot. Because it is very, very hot, the rock has melted like ice. It has become liquid, like water. It is always boiling, like water in a kettle. If you have seen a kettle boiling, you know that the steam and boiling water try to get out. The very hot melted rock inside the earth also tries to get out. Usually it cannot because the outside of the earth is tm thick and strong.
But in some places the outside of the earth is thin and weak. Sometimes a crack appears. The hot melted rock, which we call "lava" (熔岩), pushes out through the crack and bursts through. Steam and gas shoot up into the air and the hot melted lava pours out. Big pieces of rock may be thrown high into the air.
After a while the volcano becomes quiet again. The melted lava becomes hard. Later the same thing happens again and again. Each time more hot lava po
A. liquid
B. water
C. smoke
D. hard

[填空题]Volcanoes can influence the global climate.

[填空题]

Blasts from the Past

1 Volcanoes were destructive in ancient history. Not because they were bigger, but because the carbon dioxide they released wiped out life with greater ease.
2 Paul Wignall from the University of Leeds was investigating the link between volcanic eruptions and mass extinctions. Not all volcanic eruptions killed off large number of animals, but all the mass extinction cover the past 300 million years coincided with huge formations of volcanic rock. To his surprise, the older the massive volcanic eruptions were, the more damage they seemed to do.
3 Wignall calculated the "killing efficiency" for these volcanoes by comparing the proportion of life they killed off with the volume of lava that they produced. He found that size for size, older eruptions were at least 10 times as effective at wiping out life as their more recent rivals.
4 The Permian extinction, for example, which happened 250 milli

[填空题]