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San Francisco is built on 40 hills and some are very ________.  

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After Peter had returned from the Sahara desert, he was confined to bed by a ________ disease.  

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Thanks to pictures taken by satellites, deserts have not ________ a mystery in our time. 

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In the northern part of the Simpson Desert, the dunes are separated by ________ of low, open shrubland.  

Choose the word that is closest in meaning to the underlined word. 

We used to climb up the crest of the hill to get a good view of the surroundings. 

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The Sahara contains complex linear dunes that are ________ by almost 6kilometers. 

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If the deserts are ________ managed, there may be troubles for scientific expeditions.

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Deserts are also classified by their ________ location and dominant weather pattern.