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41. Under a provision of the Constitution that has never been applied. Congress is required to call a convention to consider possible amend­ments to the document when formally asked to do so by the legisla­tures of two-thirds of the states.

42. The current administration, worried about the removal of some foreign trade barriers and the failure of our exports to increase as a result of deep cuts in the value of the dollar, has formed a group to study ways to sharpen our competitiveness.

43. In the minds of many people living in England, bore Australia was Australia, it was the antipodes, the opposite pole to civilization, an obscure and unimagin­able place that was considered the end of the world.

44. Using a Doppler ultrasound device, a physician can detect fetal heartbeats by the twelfth week of pregnancy.

45. Delighted by the reported earnings for the first quarter of the fiscal year, the company manager decided to give her staff a raise。

46. A study commissioned by the Department of Agricul­ture showed that if calves exercise and associate with other calves, they require less medication and gain weight more quickly than those raised in confinement.

47. Displays of the aurora borealis, or "northern lights," can heat the atmosphere over the arctic enough to affect the trajectories of ballistic missiles and induce electric currents that can cause blackouts in some areas and corrosion in north-south pipelines.

48. The golden crab of the Gulf of Mexico has not been fished commercially in great numbers, primarily because it lives at great depths-- 2,500 to 3,000 feet down.

49. The cameras of the Voyager II spacecraft detected six small, previously unseen moons circling Uranus, doubling to twelve the number of satellites now known to orbit the distant planet。

50. A baby emerges from the darkness of the womb with a rudimentary sense of vision that would be rated about 20/500; an adult with such vision would be deemed legally blind.