The boy often gives a satisfactory answer to the teacher’s question， just a minute.
So he’s usually the teacher’s pet.
A. thought
B. having thought
C. and to think
D. thinking
网友回答
A. thought
(答案→)B. having thought
C. and to think
D. thinking
解析：-ing形式短语作状语,且think(思考)表示的动作发生于give a satisfactory answer之前,故用having thought。