crust
noun uk/krʌst/ us/krʌst/
[ C or U ]（某物的）硬皮，外壳
a hard outer covering of something
pie crust (= the cooked pastry on top) 馅饼皮
the earth's crust 地壳
[ C ]面包皮
the outside layer of a loaf of bread
Could you cut the crusts off the sandwiches, please? 请把三明治的面包皮切掉，好吗？