单项选择题 Geographers and historians have traditionally held the view that Antarctica was first sighted around 1820, but some sixteenth-century European maps show a body that resembles the polar landmass, even though explorers of the period never saw it. Some scholars, therefore, argue that the continent must have been discovered and mapped by the ancients, whose maps are known to have served as models for the European cartographers. Which of the following, if true, is most damaging to the inference drawn by the scholars

单项选择题 Assume that Tom is employed and does not have a lowpaying job. Which one of the following statements, when added to this assumption, contradicts the original statement made in the statement above

单项选择题 Which one of the following conclusions CANNOT be validly drawn from the statement above