商店、学校、机关等,若看作一个地点(point)用at,若看作一个场所(place)用in。如: I met him at the post-office. I’m now working in the post-office.
第二,介词in,on,at表示方位时的用法区别: 介系词in表示的方位是在某事物的内部,占去某物一部分,如: There is a river in the picture.(河流在图画里面,也就是说河流是画上去的,不是真的) The pen is in the pencil case. What is there in the trunk? 介系词on表示的方位,是在某事物的上面,支撑在表面上,强调接触,如: There is a pen on the picture. (钢笔在图画上面,是真的,是可以拿来写字画画的,不是画上去的) There are some mosquitoes on the ceiling. What is there on the menu? 介系词at表示的方位是一个点,例如: at home We arrived at our school. The boy threw the bone at the dog.