above 一般指位置高于某物，但不一定在正上方，也不接触另一物，其反义词是below。
on 指与另一物表面相接触。
over 指一物在另一物的垂直上方，多暗示悬空，但也含“覆盖于……之上”之意。其反义词是under。
参考例句
1. The helicopter is staying over our heads. 那架直升机就在我们头顶的上方。
2. Try whether you can jump over it. 试试看你能否从上面跳过去。
3. You can see an airport over there. 你可以看见那儿有一个机场。
英英解释
n.
1. (cricket) the period during which a given number of balls (6 in England but 8 in Australia) are bowl
2. having come or been brought to a conclusion
3. at or to a point across intervening space etc.
4. throughout an area
5. throughout a period of time
6. beyond the top or upper surface or edge; forward from an upright position
7. over the entire area
网络释义
over 煎两面荷包蛋;
超过，在...之上;
超穴球， 过穴球;
星际亿行团;
get over 克服，解决(问题等);
(从疾病、失望等)中恢复过来;
克服;
完成;
run over 把…很快地(或粗略地)过一遍;
在…上驶过，(撞倒并)碾过;
（跑）过去;
浏览;
