singular/U the large area of salt water that covers most of the surface of the Earth 海；海洋 | Tim went swimming in the sea. 蒂姆去海里游泳了。 |
| He had a room overlooking the sea. 他有一间朝海的房间。 |
| We’ re renting a house by the sea (=close to the sea) . 我们在海边租了一所房子。 |
| into the sea I ran across the beach and into the sea. 我穿过沙滩，跑进大海。 |
| at sea (=in a boat or ship on the sea) Some older tankers need maintenance while at sea. 在船上；在海上 |
| by sea (=in a ship across the sea) Most of his belongings will be transported by sea. 由海路；乘海船 |
| out to sea (=out onto the sea) She rowed the boat out to sea. 出海 |
| lost at sea (=died in the sea) A service was held to commemorate those lost at sea. 遇海难 |
| put to sea (=start a journey in a ship) The cruiser put to sea yesterday from the port of Murmansk. 启航；出航 |
| the open sea (=a part of the sea far from land) The yacht was on the open sea in light winds. 外海；公海 |
| | a | C the condition of the sea , especially the way it is affected by the weather 海面状况（尤指受天气影响的情况） | | calm/rough/choppy/stormy seas A fishing boat is missing in rough seas off the Shetlands. 一艘渔船在设得兰群岛外的汹涌海浪中失踪。 | | The sea was very choppy (=with many small waves) . 海面波浪滔天。 | |
| | b | C a large area of salt water 内海；海域 | | The dam will create an enormous inland sea. 大坝将制造出一个巨大的内陆咸水湖。 | |
| | c | singular used as part of the name of a sea （用于海名）海 | | the North Sea 北海 | | the Irish Sea 爱尔兰海 | |
| | d | the sea in general 海洋 | | the peace and freedom of the seas 海洋的平和与自由 | |