David is clever and quick at work he is honoured with the title of model worker.A. whichB.

问题补充：

David is clever and quick at work,he is honoured with the title of model worker.

A. which

B. where

C. for it

D. for which

答案：

A. which

B. where

C. for it

(答案→)D. for which

解析：考查非限制性定语从句。句意“大卫很聪明，工作很快，他因此被授予‘模范工人’称号。”for which“因为（这件事）”，表原因。故选D。