the boy seated himself in the corner with his back ___to his back

题目

the boy seated himself in the corner with his back ___to his back
a turning b to turn c to be turned d turned

答案

D
turned to his back 在这里是过去分词短语作宾语补足语,表状况
turn 和前面的宾语 his back 为被动关系,故用过去分词