Consider the professor's desk and all the prepositional phrases we can use while talking about it. You can sit before the desk (or in front of the desk). The professor can sit on the desk (when he's being informal) or behind the desk, and then his feet are under the desk or beneath the desk. He can stand beside the desk (meaning next to the desk), before the desk, between the desk and you, or even on the desk (if he's really strange). If he's clumsy, he can bump into the desk or try to walk through the desk (and stuff would fall off the desk). Passing his hands over the desk or resting his elbows upon the desk, he often looks across the desk and speaks of the desk or concerning the desk as if there were nothing else like the desk. Because he thinks of nothing except the desk, sometimes you wonder about the desk, what's in the desk, what he paid for the desk, and if he could live without the desk. You can walk toward the desk, to the desk, around the desk, by the desk, and even past the desk while he sits at the desk or leans against the desk.

All of this happens, of course, in time: during the class, before the class, until the class, throughout the class, after the class, etc. And the professor can sit there in a bad mood [another adverbial construction].

1.     in 表示方位， “在……之内”，即小地方在大地方之内。

China is in the east of Asia. 中国在亚洲东部。(中国是亚洲的一个国家，处于亚洲的范围之内)

Datong is in the north of Shanxi. 大同在山西北部。(大同是山西的一座城市)

Shandong lies in the east of China. 山东在中国的东部。(山东是中国东部的一个省份，是中国的领土，在中国的疆域之内)

The tree can be found only in the south of China. 那种树只有在中国南部才看得到。(暗指这种树只生长在中国南部地区)

The sun rises in the east and sets in the west. 太阳东升西落。

说明：表示地理位置时，be，lie 以及 be located可以互换使用。

2. on 表示方位，“在……端/边”，即一个地方在另一个地方的某一端或某一边，两个地方只是相邻或接壤，却互不管辖。

Henan Province is on the southeast of Shanxi. 河南省在山西的东南边。(河南省与山西在地理位置上是连在一起的，即两者相邻，却互不管辖)

China faces the Pacific on the east. 中国东临太平洋。(中国与太平洋相邻)

The country is bounded on the east by the sea.那个国家东边与海接界。(暗指该国为沿海国家)

Gansu Province is on the north of Sichuan Province. 甘肃省在四川省的北边。(甘肃省与四川省在地理上也是连在一起的，但互不管辖)

3. to 表示方位，“在……面”，即一个地方在另一个地方的范围之外，互不管辖。尤其当两个地方相隔较远，且有湖泊、大海等区域相隔时，通常用 to。

Japan is to the east of China. 日本在中国的东面。(日本在中国范围之外，且有日本海分隔)

Taiwan is to the southeast of Fujian Province. 台湾在福建省的东南面。(台湾在福建省的范围之外，且两者之间有台湾海峡分隔)

Taiyaun is to the west of Shijiazhuang. 太原在石家庄的西面。(太原和石家庄分别为两座城市，地理位置上互不相连，也互不管辖)

There is a beautiful zoo to the east of the station. 车站东面有一座景色宜人的动物园。

4. 把河流、山脉、铁路等事物当做两地的分界线或基点，且不说明河流、山脉、铁路等是属于哪一方，通常使用介词 to，译为“以……(方向)”。此外，表示一个地方离另一个地方有多远，也用 to。

Land to the east of the Urals is called Asia；land to the west， Europe. 乌拉尔山脉以东的陆地称为亚洲；以西的陆地称为欧洲。

The park lies to the north of the hill. 那座公园在山的北面。

The little town lies about two hundred miles to the west of Xi’an. 那座小城镇位于西安以西约两百英里远的地方。

试比较：

The school is located to the south of the city. 那个学校在本市的南面。(该学校在本市范围之外)

The school is located in the south of the city. 那个学校在本市的南部。(该学校在本市范围之内)