题目内容
32.Many experiments_____before the research team was able to get the exact data to carry on project.
A.have done | B.had been doing | C.had been done | D.have been done |
C
解析
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题目内容
32.Many experiments_____before the research team was able to get the exact data to carry on project.
A.have done | B.had been doing | C.had been done | D.have been done |
C
解析