When used in the locative sense, what's the different usages between at, in and on?
【正确答案】：Generally speaking, when used in the locative sense, at is associated with a point, on with a line or the surface of something, and in with an area or the volume of something. At is used with names of places which are considered as points. When we think of a town as being a spot on a map, contrasted with other spots, we usually use at. However, when we think of the town as consisting of houses, streets, etc., and we want to contrast being inside this area with being outside, we usually use in. Therefore, we need to use in for sizable territories. And we usually use on to indicate positions associated with a line or the surface of something.
