Question

【题目】_______ scientists have learned a lot about the world, there is much we still don't know.

A.IfB.ThoughC.SinceD.Unless

Answer 1

【答案】B

【解析】

句意：虽然科学家们对这个世界了解很多，但还有很多我们还不知道。

考查连词辨析。If如果；Though 尽管；Since自从； Unless除非，如果不。根据“there is much we still don't know.”可知，此处是Though引导的让步状语从句。根据题意，故选B。