1. ______ scientists have learned a lot about the universe, there is much we still don't know. (安徽卷) A. Once
解析：本题选择C. 本题考查状语从句。 通过句意看：表让步。
句意：虽然科学家已经对宇宙了解颇多，到那时仍旧有很多我们还无法知道的东西。
______ scientists have learned a lot about the universe, there is much we still don't know. A. Once 表时间 一旦 C. Though 小练习:
(2011全2)19．It was a nice meal, _______a little expensive. A．though B．whether C．as D. since
B. Since 表时间、原因
B. Since
C. Though
D. Unless
D. Unless 表条件
解析：本题选择A. 本题考查状语从句。 通过句意看：表让步。
句意：虽然有点贵，但是饭菜很好吃。 It was a nice meal, _______a little expensive.
A．though B．whether C．as D. since It was a nice meal, though a little expensive. （省略句） = It was a nice meal, though it was a little expensive.
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