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Read the following passage and then choose the best answer for each question
Most of our planet is covered by water. There is so much of it that if all the mountains of the world were leveled and their debris dumped into the oceans, the surface of the globe would be entirely submerged beneath water to a depth of several thousand meters. The great basins between the continents, in which all this water lies, are themselves more varied topographically than the surface of the land. The highest terrestrial mountain, Mount Everest, would fit into the deepest part of the ocean, the Mariana Trench, with its peak a kilometer beneath the surface. On the other hand, the biggest mountains of the sea are so huge that they rise above the surface of the water to form chains of islands. Mauna Kea, the highest of the Hawaiian volcanoes, measured from its base on the ocean floor, is more than 10,000 meters high and so can claim to be highest mountain on the planet.
The seas first formed when the Earth began to cool soon after its birth and hot water vapor condensed on its surface. They wore further fed by water gushing through volcanic vents from the interior of the Earth. The water of these young seas was not pure, like rainwater, but contained significant quantities of chlorine, bromine, iodine, boron, and nitrogen, as well as traces of many rarer substances. Since then other ingredients have been added. As continental rocks weather and erode, they produce salts that are carried in solution down to the sea by rivers. So, over millennia, the sea has been getting saltier and saltier.
Life first appeared in this chemically rich water some 3.5 billion years ago. We know from fossils that the first organisms were simple single-celled bacteria and algae. Organisms very like them still exist in the sea today. They are the basis of all marine life, indeed. Were it not for these algae, the seas would still be completely sterile and the land uninhabited.
- The word “debris” in line 1 is closest in meaning to
- The writer mentions Mount Everest in line 5 in order to
- The word “they” in line 12 refers to
- According to the passage, which of the following has contributed to the sea becoming increasingly salty?
- Which of the following is mentioned as part of the foundation of all life in the sea?
- Where in the passage does the author mention the processes that led to the creation of the seas on Earth?
- The word submerged, in line 1, is closest in meaning to
- The word terrestrial, in line 4, can be replaced by
- The word ingredients, in paragraph 2, is closest in meaning to