_____ they are very tired, they feel happy because they’ve finally finished their project.
A. So B. Although C. If D. But
_____ they are very tired, they feel happy because they’ve finally finished their project.
A. So B. Although C. If D. But
B
解析:考查连词。分析句意可知，他们虽然很累，但很快乐，前半句是让步状语从句，用although。