The child was lost in the forest where he was the mercy of wild beasts.A. inB. onC. forD

问题补充：

The child was lost in the forest, where he was the mercy of wild beasts.

A. in

B. on

C. for

D. at

答案：

A. in

B. on

C. for

(答案→)D. at

解析： at the mercy of完全受……支配，任由……摆布。