What Are The Rules For Using The Prepositions "At", "In", "On"?

The prepositions 'at', 'in', and 'on' are also referred to as locational prepositions. These prepositions are also used to denote time, especially 'in' and 'on'. These have specific rules governing their usage. When using these three as locational prepositions, there are certain rules that you need to follow. The preposition 'at' is used to indicate a point around which an incident or event is centred – arrived at the bank.' It can be used to denote location, direction, or destination.

The preposition 'in' is used to indicate are or volume – 'in the United States of America.' It is also used to indicate an activity or event inside a closed area. E.g. – 'in the car'. When you use 'in', the fact of an enclosed space is implicit.

The preposition 'on' is used to indicate 'surface'. It can be used to denote either a closed or an open surface – 'on the table.'

When using prepositions to denote time, we use the three we have discussed here – at, in , and on, but from a different perspective. We use 'at' to denote an event at a precise time – 'at 5 p.m.' We use 'in' to denote something in a month, year, century, etc., generally for long periods that are not too specific to a point – 'in the month of September.' We use 'on' to denote an event or incident on a specific day or a date – 'on Tuesday.'

I found the following sentences used in a prepositional quiz as the correct answers:
She is an expert in psycholinguistics.
She specializes on dialects.
Can you explain the use of "on" in the second sentence?

You specialize 'in' a field or area of expertise. The second sentence is wrong.

'in' may connote enclosure, but I am often 'on' a bus, train or plane - which are all enclosed spaces, have historically been enclosed, and in the3 case of a plane, o not imply standing to justify the use of 'on' what gives?