Scientists say it will be five or six years it is possible to test this medicine on human

发布时间：2020-08-16 20:41:11

Scientists say it will be five or six years      it is possible to test this medicine on human patients.
A. before
B. that
C. since
D. when

网友回答

(答案→)A. before
B. that
C. since
D. when
解析：此题考查时间状语从句的引导词。由It + be + 时间段 +before 从句“要过多久才…”可知，此处用before 。
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