2、The diamond is the hardest natural substance in the world． What causes this superhardness? Pressure and heat are the answers． The pressure has to be close to two million pounds． That’s per square inch． Much heat is required too． Experts say over 5,000 degrees． To make a diamond, one more thing is needed． This is ______． Pressure, heat, and carbon combine． They create a sparkling diamond． The very best are colorless． Pale blue stones─very rare─are high quality too．

    Where do most diamonds come from? Over 97 percent come from Africa． The first diamond in Africa was not found by miners． Children found it, in 1866． They were playing in a shallow stream． One picked up “a pretty pebble”． The “pebble” was placed on the mantel of the fireplace． It was soon forgotten． Much later, a guest noticed the sparkle． He urged the farmer to have the stone looked at． He did． He took it to an expert in town． The “pebble” proved to be a diamond worth ＄2,500． That was a small fortune in those days． To date, the mines in Africa have produced over 1 billion dollars worth of diamonds．

    Not all diamonds are found in Africa． Our hemisphere produced diamonds too． Brazil was a big producer in earlier times． The famous gem the Star of the South was found in brazil in 1853．

    The gem the President Vargas was found more recently in Brazil． This was in 1938． A poor prospector found the stone． It was in the San Antonio River． It weighed 726．6 carats． The man sold the stone for ＄10,000 to a local broker． The broker almost immediately resold it． He got about ＄425,000． What a nice guy!

1．What is the best title of the passage? （Please answer within 10 words）

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2．Which sentence in the passage can be replaced by the following one?

    Some diamonds are found in Africa but some are not．

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3．Please fill in the blank in the first paragraph with proper words or phrases to complete the sentence．（Please answer within 10 words）

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4．What do you think of the diamond in modern days?（Please answer within 30 words）

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5．Translate the underlined sentence in the first paragraph into Chinese．

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