So although Fleming discovered penicillin, it was over a dec


So although Fleming discovered penicillin, it was over a decade ___________someone else turned penicillin into the great drug of the 20th century.
A.when B.that C.before D.unless
Elainechou 1年前 已收到1个回答 举报

lina136 春芽

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C

考查时间状语从句。句意“尽管是弗莱明发现的青霉素,但是青霉素广泛用于药物是几十年后的事情。”it is +一段时间+before意为“过了多久才......”。故选C。

1年前

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