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How Native Americans developed corn is a puzzl
问题详情
How Native Americans developed corn is a puzzling, for no wild com has ever been discovered.此题为多项选择题。请帮忙给出正确答案和分析，谢谢！
参考答案
正确答案：puzzling—puzzle
考查词性。冠词a后应该加可数名词单数，puzzling是形容词，应改为名词puzzle。
考点：
