B2 a large mammal that eats fish and lives partly in the sea and partly on land or ice海豹
a seal pup
The plan to cull large numbers of baby seals has angered environmental groups.
We could see seals on the rocks, basking in the sun.
We spied a seal from the shore.
We sailed past a group of seals.
something fixed around the edge of an opening to prevent liquid or gas flowing through it密封垫；密封装置
a thin piece of material such as paper or plastic that covers the opening of a container and has to be broken in order to open the container and use the contents封口
an official mark on a document, sometimes made with wax, that shows that it is legal or has been officially approved封蜡；印章；封条
C2 to close an entrance or container so that nothing can enter or leave it封，密封
to cover a surface with a special liquid to protect it（用特殊液体）封盖…的表面
C2 to close a letter or parcel by sticking the edges together封上（信或包裹）
The top of the bottle is then sealed with green wax.
To ensure that the bottles of ink are not tampered with, the lids will be sealed with plastic.
Make sure that any gaps around the edge of the bath are sealed.
Seal the bags before they go in the freezer.
Food sealed in foil pouches lasts for a long time.
to make an agreement more certain or to approve it formally确认，正式批准（协议）