请辨析 distinguish, discern, discriminate 和 differentiate。
这四个词在作“区分”“辨别”解时，是同义词，但有些细微的区别。然而，作为托福等类考试的考生，可以不去花太多的时间去辨析它们，只要记住它们在作“区分”“辨别”解时，是同义词，因而常常可以互换，就行了。因为托福等类的考试经常有这类同义词互换的考题。
请做下面的英语试题：
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The fact that economists are able to distinguish virtually all of the causes of recessions does not mean they can accurately predict them. A. prevent B. discern C. promote D. define
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Not until they were able to discern the Statue of Liberty did many European immigrants to the United States really believe they would reach their destination. A. pass by B. make out C. embrace D. visit
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Bill can discern between good and bad. A. prospect B. anticipate C. distinguish D. outlook
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In ancient Egyptian paintings, royal figures were differentiated by making them several times larger than others. A. distinguished B. estranged C. deferred D. enlarged
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Colorblind people often find it difficult ____ between blue and green. A. to separate B. to compare C. to contrast D. to distinguish(大学生竞赛题)