http://zhidao.baidu.com/question/41221465.html
一年前的帖子, 很全面。
“一. in, to, on和off在方位名词前的区别
1. in表示A地在B地范围之内。如:
Taiwan is in the southeast of China.
2. to表示A地在B地范围之外,即二者之间有距离间隔。如:
Japan lies to the east of China.
3. on表示A地与B地接壤、毗邻。如:
North Korea is on the east of China.
4. off表示“离……一些距离或离……不远的海上”。如:
They arrived at a house off the main road.
New Zealand lies off the eastern coast of Australia. ”