以及on the left， right向左向右，on the stair在台阶上等。

步行、驴、马、玩笑on，cab，carriage用in

例：On foot步行； on horse骑马； on donkey 骑驴。

He rode on， blood flowing from his side. 他骑着马，鲜血从腰部流下来。

The soldier of the Eighth Route Army rode 100 li on a horse a day in order to catch up with his unit. 为赶上部队，那位八路军战士骑马日行百里。

Go on horse back！ 骑马去！

You are having me on！ 你和我开玩笑呢！

in cab和in carriage 不能用on或by cab或carrige.

at山脚、门口在当前，速、温、日落价核心

即在山脚下、在门口、在目前，速度、以……速率、温度、在日落时、在……核心要用at.

例：At the foot of the mountain， there are thirty of our comrades. 在山脚下，有我们30个同志。

There is a beautiful lake at the foot of the hill. 山脚下有一个美丽的湖。

At the gate of the house there are many children playing glassball. 门口有一大群孩子在玩玻璃球。

Who‘s standing there at the door？ 谁站在门口？

I don‘t need the dictionary at present. 我现在还不需要这本词典。

He is at present in Washington. 他目前正在华盛顿。

The train runs at fifty kilometres an hour. 火车每小时行驶50公里。

we built the plant at top speed and minimun cost. 我们以最低的投资，最高的速度修建了该工厂。

at home 在国内，在家里

at ten degrees centigrade 在摄氏10度

at minus ten degrees centigrade 摄氏零下10度

Water freezes at 0°centigrade. 水在镊氏零度结冰。

Water usually boils at 100°。 水通常在摄氏loo度沸赐。

at zero 在零度

at the rate of 45 miles an hour