Ⅰ.in 表示“在某范围之内”，如：
① In the Northwest, there will be snow in the night.
② Beijing is in the north of China.
Ⅱ.on 表示“两地接壤”。如：
① Tianjin is on the north of Beijing.
② Jiangshu is on the south of Shandong.
Ⅲ.to 表示“在某范围之外，两地不接壤”。如：
① There will be a strong wind to the north of the Huai River.
② Japan is to the east of China.