Without a sure supply of water farming in that area remains at the of the weather.A. disp

问题补充：

Without a sure supply of water, farming in that area remains at the of the weather.

A. disposal

B. risk

C. cost

D. mercy

答案：

A. disposal

B. risk

C. cost

(答案→)D. mercy

解析：考查名词辨析与搭配。at the mercy of任凭…的摆布，完全受…的支配；at(或in)sb’s disposal任某人处理，供某人使用：I had no time at my own disposal. 我没有一点自由支配时间。at the risk of冒…的风险；at the cost of以…为代价。句意为：没有稳定的水源供应，那个地区的农业依然靠天吃饭。