Tough the task was, we finish it ahead of time and therefore we were highly praised for

Tough the task was, we finish it ahead of time and therefore we were highly praised for it.
A. though; would
B. although; had to
C. as; were able to
D. though; must

A. though; wouldB. although; had to(答案→)C. as; were able toD. though; must解析：考查as的倒装句以及固定用法。Be able to do sth指经过努力能够做某事；have to指客观上不得不做某事；本题重在掌握as“尽管”时可引起倒装，同时although引导让步状语从句时不能倒装，as引导让步状语从句时必须倒装，而though引导让步状语从句时可以倒装也可以不倒装。句意：尽管这个任务很难，我们还是能够提前完成的，因此我们会因此得到高度赞扬。故C正确。

感谢回答，我学习了