In the last paragraph the word "persistent" means

试卷相关题目

• 1If an intense sunspot activity-had occurred in 1857, the next one would have been in

  A.1858.

  B.1862.

  C.1865.

  D.1868.

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• 2The leading spot and the following spot are the names of

  A.two large sunspots.

  B.a large spot and a small spot.

  C.the two spots in a spot pair.

  D.the central core and the ring around it.

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• 3Sunspots are cooler than the rest of the sun's surface because

  A.they produce less energy.

  B.they are buried in the sun.

  C.they are far away from magnetic fields.

  D.they are close to magnetic fields.

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• 4Careful observations and systematic studies of sunspots

  A.were made by ancient astronomers.

  B.started in the early 17th century.

  C.were made by Galileo only.

  D.could be made without a telescop

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• 5Which of the following is NOT true of working class Americans、

  A.They work long hours．

  B.They live from paycheck to paycheck．

  C.They don't want to be healthy eaters．

  D.They want to save money for presents．

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