U 海，海洋 the salt water that covers most of the earth's surface and encloses its continents and island

　command the ～　掌握制海权
　cross the ～　横渡大海
　enter the ～　入海
　explore the ～　探索海洋
　face the ～　面对大海
　flow into the ～　流入大海
　follow the ～　当海员
　go down the ～　到海边去
　go to ～　当水手
　guard the ～　守卫海洋
　love the ～　爱大海
　put out to ～　出海
　put to ～　出航
　ride the ～　航行于海上
　sail the ～　航海
　sweep the ～　（船）在海上到处航行
　take up the ～ as career　当海员
　travel by ～　海上旅行
　angry ～　愤怒的海
　blue ～　蔚蓝的海
　calm ～　风平浪静的海
　close ～　领海
　continental ～　内海
　deep ～　深海
　heavy ～　波涛汹涌的大海
　high ～s　公海
　inland ～　内海，咸水湖
　long ～　长波阔浪的海面
　open ～　公海，大海
　raging ～　波涛汹涌的海洋
　rough ～　波涛汹涌的海洋
　short ～　急浪翻腾的海面
　smooth ～　平静的海面
　vast ～　广阔无垠的大海
　wide ～　宽阔的大海
　the Caribbean S-　加勒比海
　the Dead ～　死海
　the Four Seas　英国周围的四海
　the Mediterranean S-　地中海
　the North ～　北海
　the South ～　南海
　the Yellow ～　黄海
　～ bed　海床
　～ creatures　海洋生物
　above the ～　海拔以上
　at ～　在海上
　storm at ～　海上风暴
　by the ～　在海边
　town by the ～　海滨城镇
　in the ～　在海里
　current in the ～　海中的潮流
　arm of the ～　海湾
　surface of the ～　海面
　on ～　在海上
　adventure on ～　海上的冒险
　victory on ～　海上的胜利
　over the ～　在海外
　a ～ of　大量，广阔，一片
　a ～ of people　人海
　a ～ of red flags　红旗如海
　a ～ of troubles　无穷的麻烦
　a golden ～ of wheat　一片金黄色的麦子

　The sea bounds the peninsula on the sides.　该岛三面环海。
　The sea and the sky seemed to blend into each other.　大海和蓝天似乎连成了一片。
　The sea cast up shells on the beach.　海水把贝壳冲到沙滩上来了。
　The sea calmed down as soon as the wind fell.　风平浪静了。
　The sea gradually calmed down as we steamed out.　我们的轮船开出去时，海面逐渐平静下来了。
　The wind blew hard and the sea was billowing.　风吹得很大，海上巨浪翻滚着。
　The roaring sea gradually calmed down.　咆哮的大海逐渐平静下来。
　The rise and fall of the sea is governed by the movements of the moon.　大海的涨潮和退潮是由月亮运动引起的。
　The Yellow Sea is gaining on the land along the coast.　黄海侵蚀着沿岸的陆地。
　The Baltic Sea is going down.　波罗的海变得平静下来。
　Forts were framed for defence against land or sea forces, but useless against an air attack.　建筑城堡是为了防御陆海军入侵，但对于空中打击就无效了。
　Very big waves dashed over the sea wall at the height of the storm.　在暴风雨最猛烈的时候，巨浪吞没了海堤。
　The two nations have been contending about the rights to deep sea fishing in their waters.　这两个国家一直为他们水域中的深水捕鱼权问题争吵不休。
　The seas were running eight feet and building.　海浪有八英尺高，而且还在增大。
　The boat sailed into quieter seas.　船驶入更加平静的海域。

 ♣ a sea of
　无限的，很多的　much, lots of
　〔说明〕 a sea of后可接复数名词，也可接不可数名词，后接复数名词用作主语时谓语动词一般用于单数形式；强调一个个的个体时，谓语动词也可用于复数形式。
　I don't want to add you a sea of troubles.　我不想给您添麻烦。
　We must face a sea of troubles and bear it.　对这困难我们必须正视，必须忍受。
　If you had attended to my advice, you would not be in a sea of troubles now.　要是当时你听了我的劝告，你现在就不至于苦恼了。
　You're really asking for a sea of troubles speaking to me like that.　你这样对我讲话，真是自找麻烦。
　A sea of faces betrayed their grief.　无数面孔的表情流露出内心的悲伤。
　A sea of faces beamed with joy.　无数面孔面露喜色。
　There's a sea of troubles ahead.　今后还有无穷尽的麻烦呢。
　The streets are decked with a sea of red flags.　街道上红旗似海。
　Round him surged a sea of noise.　她的周围是一片沸腾的闹声。

 ♣ at sea, by sea, by the sea, in the sea, on the sea
　这五个短语的意思不同。其区别在于：
1. at sea的意思是“航行中”“作海员”“茫然”。例如：
　By the second day, the ship was well out at sea.　第二天该船顺利出航。
　He has two sons in the army, and a third at sea.　他有两个儿子在陆军，第三个儿子当水手。
　The man has a son at sea.　这人有个当水手的儿子。
　I felt completely at sea when I first arrived in this country.　当我初到这个国家时，感觉全然迷惑了。
　We were all at sea until instructions arrived.　接到指示前，我们都茫然不知所措。
2. in the sea的意思是“在海里”。例如：
　Children were bathing in the sea.　孩子们在海里游泳。
　I bathed in the sea nearby twice a week.　我曾在附近的海里一周游两次泳。
　He used to bathe in the sea after supper.　晚饭后，他经常去海中泡水取凉。
3. by sea的意思是“由海路”“乘船”。例如：
　The storm has interrupted all travel by sea.　暴风雨使所有海上旅行中断了。
　Going by sea seems a good bet.　乘船去似乎是恰当的选择。
　Are you going out by sea?　你是乘船出国吗?
　I will go to Chicago by sea.　我将乘船去芝加哥。
4. by the sea的意思是“在海边”。例如：
　They pitched camp by the sea.　他们在海边扎营。
　The couple spent all day by the sea, and motored to the hotel in the evening.　这对夫妇白天在海边呆了一天，晚上乘车回旅馆。
　The children enjoyed playing by the sea, kicking up the sand into each other's faces.　孩子们喜欢在海边玩耍，把沙子踢到伙伴的脸上。
5. on the sea的意思是“在海上”，常与ship, boat, sail等连用。例如：
　Boats sail on the sea.　船航行于海上。
 ♣ 下面两组中短语的意思不同：
　
　
 ♣ sea, ocean
　两词的意思不同，前者是海，后者是洋，在面积的划分上，海是洋的一部分。

1. 知识的海洋深而广。
　［误］ The knowledge sea is deep and broad.
　［正］ The sea of knowledge is broad and deep.
　［析］ sea不受其他名词修饰，但sea of可修饰其他名词，如 a sea of faces （无数面孔）， a sea of troubles （无穷的麻烦）， a sea of red flags （红旗似海）等，都是形容数量之多。
2. 他到海边度假去了。
　［误］ He went to sea for his vacation.
　［正］ He went to the sea for his vacation.
　［析］ go to the sea(= go to the seaside)表示“到海边去”， go to sea(= become a sailor)表示“出海，当水手”。
3. 我们经常在海里游泳。
　［误］ We often swim on the sea.
　［误］ We often swim at sea.
　［正］ We often swim in the sea.
　［析］ “在海里游泳”是swim in the sea, at sea指在海上航行， on the sea指“在海上，在海边”。
4. 大约四分之三的地球被海水覆盖。
　［误］ About three quarters of the Earth is covered by seas.
　［正］ About three quarters of the Earth is covered by sea.
　［析］ sea表示“海水”时为不可数名词；但当 sea作“海浪”或“汹涌的波涛”解时多作复数。
5. 我不懂这问题，我茫然不知所措。
　［误］ I can't understand this problem; I'm all at the sea.
　［正］ I can't understand this problem; I'm all at sea.
　［析］ sea往往和all或completely连用，构成 be all〔completely〕 at sea的结构，表示“茫然”“摸不着头脑”， sea前面不加冠词。

　［同义词］ deep, ocean, waves
　［反义词］ air, land
　［词源］　古英语sæ（海洋）