肺部有一层薄膜保护内部组织免受感染。

The lungs are protected by a thin ___membrane that prevents infections.

这种特殊薄膜可以防止液体渗透到设备内部。

The special ___membrane prevents liquid from seeping into the equipment.

这种新型过滤膜能有效分离气体混合物。

The new filter ___membrane can effectively separate gas mixtures.