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  • 更新 2022-09-03
  • 科目 英语
  • 题型 单选题
  • 难度 较易
  • 浏览 522

It could take 4-6 months before the first batch(批)of vaccines (疫苗)are available to fight A/H1N1 flu ________ as swine flu, WHO officials said.

A.known B.to know C.knowing D.having known
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