we have finished the course we shall start doing more revision work.A. For B. Now that D

问题补充：

we have finished the course, we shall start doing more revision work.

A. For B. Now that D. By now D. Until

答案：

解析：分析句子意思可以知道，该句为原因状语从句，选项C、D不符合题意。选项A表示原因，不可放在句首，故应选A项既然，由于。