a seal that must be broken when first used and cannot easily be resealed
双语例句
1
When the polymer cracks, the capsules break open and release the healing agent, which becomes polymer solid and seals the crack and restores the material's properties.
当材料断裂，荚囊就会打开并释放出修复介体，介体变成实体的复合物填补裂缝从而恢复材料的特性。
2
Polar bears can smell the seals and break in the roof, so a mother often has several dens.
北极熊可以闻到海豹的气味并打破洞穴的顶部，因此海豹妈妈通常都有好几个洞穴。
3
I think I would rather have you open it, dearest, ' said she, turning over the parcel. 'I don't like to break those great seals;