What is the difference between expert at, expert in and expert on?
Choose the correct preposition
1. John is an expert at/on/of the subject of British history.
2. Mandy is an expert in/with/on a needle and thread.

▪ expert at
▪ He's an expert at getting his own way.
▪ expert in
▪ an expert in skin care
▪ expert on
▪ an expert on European art

Question

What is the difference between expert at, expert in and expert on?
Choose the correct preposition
1. John is an expert at/on/of the subject of British history.
2. Mandy is an expert in/with/on a needle and thread.

▪ expert at
▪ He's an expert at getting his own way.
▪ expert in
▪ an expert in skin care
▪ expert on
▪ an expert on European art

Answer

There is no difference in the meaning.  But for some reason, you are an expert "on" or "in" a subject (so an "expert in/on the subject of British History", "expert in/on European art", etc.)

And you are an expert "with" an object (so an "expert with a needle thread", an "expert with a sword").

Answer

in, on and at are prepositions, they show a relationship between to words in a sentence.
- in is used more in general and for a longer period of time. example: I am not that bad in English. 
- on is used for particular days, dates, holidays. example: let us have dinner together on friday. can we meet on the 15th?
- at is used in specific times and for holidays without the word day. example: let us have dinner together at new years eve. can we meet at 3 o'clock?

Answer

he is an expert in getting things done his way

Answer

on the subject of