[解析]
(1)细节理解题。根据第一段中When the explorers landed on the moon,they discovered that the moon was full of underground cities.(当探险者登上月球时,他们发现月球上到处都是地下城市)可知,在H.G.Wells的故事中,让探险者感到惊讶的他们的地下城市。故选D。
(2)代词指代题。根据上文However,the question that the "moon people" asked is still an interesting one.(不过,"月球人"提出的问题仍然是一个有趣的问题。)可知,本句中A growing number of scientists are seriously thinking about it.(越来越多的科学家正在认真思考这个问题)it指代上文the question that the "moon people" asked,即第一段最后一句"Why are you traveling to outer space when you don't even use your inner space?"(你们连你们的内部空间都不利用,为什么却要去外太空旅行?)这个问题。由此可知,it指的是"利用地球的内部空间"。故选C。
(3)细节理解题。根据第三段Underground systems are already in place.Many cities have underground car parks.In some cities,such as Tokyo,Seoul and Montreal,there are large underground shopping areas."The Chunnel",a tunnel connecting Englandand France,is now complete.(地下系统已经就位。许多城市都有地下停车场。在一些城市,如东京、首尔和蒙特利尔,有大型的地下购物区。连接英法两国的隧道"英吉利海峡隧道"现已完工。)可知,我们已经有了停车场、购物区和隧道这样的地下系统。故选C。
(4)标题概括题。文章第一段从英国作家H.G.Wells的书中引出"Why are you traveling to outer space when you don't even use your inner space?"(你们连你们的内部空间都不利用,为什么却要去外太空旅行?)这个问题,根据第三段第一句Underground systems are already in place.(地下系统已经就位),第四段第二句Japan's Taisei Corporation is designing a network of underground systems,called "Alice Cities," (日本的Taisei公司正在设计一个地下系统网络,称为"爱丽丝城市")以及最后一段第一句Supporters of underground development say that building down rather than building up is a good way to use the earth's space.(地下开发的支持者说,向下建设而不是向上建设是利用地球空间的好方法)可知,其实,人类已经在利用地下空间建隧道、停车场、购物区及网络系统,支持者认为向下建设而不是向上建设是利用地球空间的好方法,所以短文的最佳标题为"向下建,而不是向上建"。故选B。