Amy is lying on the grass doing nothing ,grass 和doing 间要不要加介词

不用.doing 表示伴随的状态.作状语.看懂了以下句子,你的这个问题就解决了Amy is lying on the grass.She is doing nothing else.现在,你可以用分词结构合并这两句句子：1 Amy is lying on the grass ,doing nothing ...