be at grass meaning in Chinese

• 在放牧中, 闲着

• grass:    n. 1.草；牧草；牧草地，牧场；草 ...
• at grass:    在地面上
• on the grass:    在草地上

Examples

1. Is tom underground ? ” “ no , he is at grass
   “汤姆下矿井了吗? ” “不,他在坑上面。 ”
2. Be at grass
   在放牧中