-- the soldiers are very tried, they keep on working.
--They are great. We must learn from them.
A. Because; /
B. Though; /
C. Because; so
D. Though; but
网友回答
A. Because; /
(答案→)B. Though; /
C. Because; so
D. Though; but
解析：考查连词。Because因为；Though虽然，尽管； so因此；but但是；句意：虽然这些士兵很累，但是他们坚持工作。though引导的让步状语从句，不能与but同时出现在一个句子中。故选B。