由于存在着危险的下层逆流，在大部分海岸线附近游泳都不安全。Dangerous undertows make swimming unsafe along most of the coastline.那男孩逆流游去.The boy was swimming in a direction contrary to the current.我们逆流向上游游去.We swam upstream against the current....
Clubbing baby seals to death for their pelts is wrong.为了获得海豹皮而用棍棒打死幼海豹是不道德的。Check seals on fridges and freezers regularly.定期检查冰箱和冷冻柜的密封装置。They saw many seals off the Coast of Alaska.他们在阿拉斯加海岸外看见很多海豹....