adj.外壳的
n.外壳
A microphone inside each muff senses sound waves that make it through the outer ear cup, and a speaker creates pressure waves that cancel them. 耳机罩内的麦克风负责感应传入耳机外壳的声波，喇叭负责制造压力波予以抵消。
用作名词 (n.)The turtle has a very hard shell. 乌龟有很坚硬的外壳。
Its thin outer shell had protected its liquid interior. 它薄薄的外壳保护着它呈液体的内脏。
