The book which sells well is on a true story.A. basedB. focusedC. decidedD. located

问题补充：

The book, which sells well, is on a true story.

A. based

B. focused

C. decided

D. located

答案：

(答案→)A. based

B. focused

C. decided

D. located

解析：考查固定词组。Be based on…以…为基础；focus on…聚焦于…；be located in…位于…；句意：卖得非常好的这本书，是以一个真正的故事为基础的。根据句意说明A正确。