Scientists say it may be five or six years it is possible to test this medicine
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Scientists say it may be five or six years ________ it is possible to test this medicine on human patients.
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A．sinceB．afterC．beforeD．when试题答案
答案：C
解析：it在句中指时间。句意为：可能还要过五六年才有可能在病人身上试验这种药。 |