Set the wolf to keep the sheep.(叫狼看守羊;引狼入室)。
Don′t trust a goat with the kitchen-garden,or a wolf with sheepfold.(不能请羊管菜园,不能请狼管羊圈;监守自盗)。
A wolf in sheep′s clothing(披着羊皮的狼)。
To wolf down one′s food(像狼一样吃东西;狼吞虎咽)。