at sea, by sea, by the sea, in the sea, on the sea
这五个短语的意思不同。它们的区别在于：
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：
go to sea
去当水手
go to the sea
到海滨去
all at sea
迷失船位
at full sea
不知所措
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。
sea，ocean
这两个名词都可表示“海”之意。
sea普通用词，可用复数形式表单数意义。sea所指的面积要比ocean小得多。sea也可是ocean的一部分。
ocean指把海作为一个整体，是海的总称，即海洋。
