2. 外语
  3. In the past 50 years, there ______ a great increase in the amount of research on the human brain.

In the past 50 years, there ______ a great increase in the amount of research on the human brain.

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问题 In the past 50 years, there ______ a great increase in the amount of research on the human brain.
选项 A、was.., did
B、has been.., to be done
C、was.., doing
D、has, been.., done
答案D
解析 根据in the past 50 years判断，需用现在完成时；过去分词短语和不定式都能做定语，但本句想表达的是已经做了的实验，因此应用过去分词表完成和被动，选项D正确。
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