◎ 题干
It is important for the websites _______ regularly.
[     ]
A. to be updated  
B. to have been updated  
C. to update    
D. to have updated
◎ 答案
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◎ 解析
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◎ 知识点
    根据魔方格专家分析,试题“It is important for the websites _______ regularly.[ ]A. to be updated B. to have been updated C. to updateD. to have updated…”主要考查了你对  【不定式的被动式】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。