阅读理解。 The unknown world's mystery The sea is the biggest unknown part of our world.  It covers seventy-one percent of the earth.  There is still much to be discovered about this vast blanket of water.  If the waters of the ocean could be removed,the sea floor with its wide valleys,irregular mountains and rivers in the sea would be an unbelievable sight. Tourism under the deep blue sea Tourists can now explore the world beneath the waves without ever getting wet. From tourist submarines to underwater dining,undersea tourism is making a big splash. Tourist submarines (潜艇) The popularity of submarine tours has grown rapidly in the last decade.  Now,tourist submarines operate in more than 20 locations worldwide,including the waters around Okinawa and Taiwan's Green Island. The submarines carry nearly 2 million tourists each year. Large windows offer passengers spectacular views as the submarines explore colorful coral reefs and sunken ships. Most one-hour tours cost about $80. Underwater dining For a more upscale experience,tourists can enjoy fine .dining under the sea.  Last summer the Hilton Maldives Resort opened the world's first underwater restaurant,Ithaa. Diners walk down a staircase into the restaurant,which rests 35 feet beneath the waves of the Indian Ocean. Transparent walls surround the dining area,and you can treat guests to a panoramic(全景) ocean view. But this excellent view doesn't come cheap. The tasting menu costs $200 per person.Be sure to make reservations early,too. The restaurant seats only 14 people. 1. What does the author want to tell us in Paragraph 1? A. The sea is the biggest unknown part of our world. B. The sea covers seventy-one percent of the earth. C. Some information about the sea floor. D. The reasons for researching undersea tourism. 2. What does the author really mean by saying 'undersea tourism is making a big splash' in Paragraph 2? A. Undersea tourism is a new fashion in travelling. B. Your clothes will be made wet by the water splash. C. Undersea tourism is dangerous. D. There is still a long way for undersea tourism to go. 3.  Which of the following statements about tourist submarines is RIGHT? A. Tourist submarines only have a history of about 10 years. B. There are tourist submarines in every part of the world now. C. Tourist submarines have carried about 2 million tourists so far. D. People can enjoy tourist submarines in the waters around Okinawa. 4.  The walls of the restaurant Ithaa are most probably made of ______ . A. stone B. brick C. glass D. steel 5.  From the passage,we can infer that the author _____. A.  doesn't think underwater tourism is a good idea B.  shows great interest in underwater tourism C. is worried about underwater tourism D. is probably a scientist who studies