. we all tried our best we lost the game in the end.A. AsB. AlthoughC. BecauseD. Since

问题补充：

. we all tried our best, we lost the game in the end.

A. As

B. Although

C. Because

D. Since

答案：

A. As

(答案→)B. Although

C. Because

D. Since

解析：考查连词。A. 随着；B. 尽管，虽然 C. 因为D.自从……以来。句意：尽管我们尽了最大努力，最后我们还是输掉了比赛。故选B。