C．an Earth explosion D．huge waves

　　解析：选D　细节理解题。根据文章第二段中"Huge waves are created and spread outwards from the hole."可知答案。

　　3．By giving the example of dinosaurs, the author tries to prove ________.

　　A．animals could not live in the cold climate

　　B．what happened 65 million years ago was an invented story

　　C．the human beings will die out in 2094

　　D．the Earth could be hit by other objects in space

　　解析：选D　推理判断题。根据最后一段中的"Could it really happen？"以及"Will we meet the same end？"两个问题的提出可知，作者是想通过举恐龙这一例子说明地球很有可能再次遭遇撞击。

　　B

　　The human brain contains 10 thousand million cells (细胞) and each of these may have a thousand connections. Such great numbers used to

　　discourage us and cause us to stop thinking about the possibility of making a machine with humanlike ability, but now that we have grown used to moving forward at such a speed we can be less sure. Quite soon, in only 10 or 20 years, perhaps, we will be able to build a machine as complex (复杂的) as the human brain, and if we can we will. It may then take us a long time to make it as intelligent as the human brain by properly programming it.

　　I think it is certain that in decades, not centuries, machines of silicon (硅) will arise to compete with their human ancestors. In a real sense they will be able to reproduce themselves. Silicon will have ended carbon's long control. And we will no longer be able to consider ourselves to be the finest intelligence in the world.

　　As the intelligence of robots increases and their cost goes down, we may achieve a lot with their help, first on the earth through their ability to complete any kind of work in harmful environments. In the end, deserts (沙漠) may turn into gardens. Further ahead, by a combination of the great wealth this new age will bring and the technology it will provide, the creation of a huge, man­made world in space, home to thousands or millions of people, will be within our power.

　　4．In the author's opinion, the human brain ________.

A．is complex and intelligent