residue

咖啡壶底部有一层棕色残留物。

There's a brown ___residue at the bottom of the coffee pot.

杯底残留着一些咖啡渣。

There was some coffee ___residue left at the bottom of the cup.

咖啡机使用后会在壶底留下一些咖啡残渣。

The coffee maker leaves a small ___residue at the bottom of the pot after brewing.