腹背受敌

between hammer and anvil between the bark and the wood between the devil and the deep sea between the beetle and the block between you and me and the post between you and me and the bedpost between the upper and nether millstone the difference between tweedledum and tweedledee the scissors gap between the prices of .. .. and ... on the anvil upon the anvil stage between the egg and adult butterfly the relation between rice disease and potassium location between the exterior and interior contact length between the tool and chip distinctions between the enemy and ourselves pustule at the part between the first and second metacarpals horn of the anvil beak between the lines