n.子弹，弹药筒,笔芯，墨盒,暗盒，胶卷盒,录音带盒，唱头
Change the filter cartridge as often as instructed by the manufacturer.
按照生产厂家的使用说明，经常更换过滤筒。
The cartridge must be replaced at regular intervals.
弹药必须定时更换。
This rifle only holds one cartridge.
这支来复枪只能装一发子弹.