| 2005年职称英语等级考试A级
阅读理解第三篇（P338）
The Exploding Lakes of Cameroon
What comes to mind when you think of a lake? You probably imagine a pretty scene with blue water，birds，and fish.For the people in the northwestern Cameroon，however, the image is very different.For them，lakes may mean terrible disasters.（41）In 1984，poisonous gases exploded out of Lake Monoun and came down into the nearby villages，killing thirty-seven people.Two years later, Lake Nyos erupted.A cloud of gases rolled down the hills and into the valleys and killed 1,700 people.
41.What will happen when Lake Nyos and Lake Monoun explode?
A.Water will flow down the hills.
B.Poisonous gases will be released suddenly.
C.A strong wind will rise from the lakes.
D.The volcanoes will come to life.
Lake Nyos and Lake Monoun are crater（火山口）lakes.They were formed when water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake Monoun are not active anymore.However, poisonous gases from the center of the earth continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake.In most crater lakes，these gases are released often because the water turns over regularly.That is，the water from the bottom of the lake rises and mixes with the water at the top，allowing the gases to escape slowly.
（42）However，in Lakes Nyos and Monoun，there is no regular turning over.
42.Which of the following statements about Lake Nyos and Lake Monoun is true?