Question

________ he has limited technical knowledge, the old worker has a lot of experience.

1. A.
   Since
2. B.
   Unless
3. C.
   As
4. D.
   Although

Answer 1

D
句意：这位老工人虽然专业知识有限，但实践经验丰富。as可以引导让步状语从句，但必须使用倒装语序，即：Limited technical knowledge as he has…，准确理解句意，精确把握主、从句的逻辑关系是解答本题的关键。