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  3. It has been known for decades that the appearance of sunspots is roughly periodi

It has been known for decades that the appearance of sunspots is roughly periodi

游客2024-11-12  20
问题 It has been known for decades that the appearance of sunspots is roughly periodic, with an average cycle of eleven years. Therefore, the incidence of solar flares and the flux of solar cosmic rays, ultraviolet radiation, and X-radiation all vary directly with the sunspot cycle.
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答案 连词误用，应把Therefore改为And。
解析 第一句说“几十年来，人们认为太阳黑子的出现大致是周期性的，平均11年为一个周期。”第二句的意思是“太阳耀斑的发生和太阳宇宙射线、紫外线以及X射线的放射量都随着太阳黑子循环而变动。”这两句之间是并列关系，而不是因果关系，因此应用And连接。
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