_____many times, they succeeded _________ the experimentA.Having tried; in doingB.Tried; in being doneC.Having tried; to doD.Tried; doing
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A解析考查非谓语动词。主语they与try之间是主动关系，故用现在分词。分词的动作发生在谓语动词之前，所以用现在分词的完成式，短语：succeed in doing sth 成功做成某事，句意：尝试了许多次之后，他们成功的做成了实验。所以选A。