6.75 USAGE NOTE

There are some restrictions in the choice of preposition.

'At' is not usually used to indicate the place that the subject of the verb is moving to or towards. It is used to indicate what someone is looking at, or what they cause an object to move towards.

• They were staring at a garage roof.
• Supporters threw petals at his car.

'After' is used to indicate that someone or something is following another moving person or thing, or is moving in the same direction but behind them.

• He hurried after his men.
• ...dragging the sacks after us along the ground.