It would not make much logical sense to say "involved at" or "involved by" or "involved from" "involved off" "involved on" "involved to" etc. "in" and "with" are the only two that make some sense; when the choices we have have already been limited by the ancient language. To select from. Grammar point for discussion: You cold use the phrase "involved by association" by placing an appropriate word after "by" For everyday use most natives would see "involved in " or "involved with" as the same. involved with implies acting together with other people/organisations or actually doing something "she is actively involved with the buying department to procure the new equipment," involved in implies more of a one to one relationship. "she is involved in a romantic relationship with Jim"

It would be the same as using "in" and "with" for other situations. In any conversation = same as "in a hospital" or "in a train station" etc. "so she did not get involved 'in' any conversation" = she did not get involved in any single conversation with anybody on a one to one basis, or even in a group conversation. with selling and buying = same as "with" in other situations. "she went with Ali to the cinema" "she is with Ali at the cinema" So "to be involved 'with' selling and buying" = to be commercialised you have to deal "yaptIm" every day with the buying and selling activities" you are not actually "in" the buying and selling but doing it. Your will hear native speakers say either "in" or "with" for the last sentence and it would be understood by them as being the same actually "doing" the "buying and selling". I think our ancient language used "in" "on" "at" and "with" and in modern times we had to adapt the prepositions to use, to meet new modernity, inventions, trade practices etc. You may have to wait for the better teachers on italki to answer the grammar points. To see how they apply to todays teaching and what is expected for tests and exams.

Involved in means become associated emotionally or sexually. We use 'with' to prevent a repetition within the paragraph. Suppose, I am involved in a romance with her.