Student or Learner
I closed my book to join in the conversation.
Why IN is used here? Cant we simply say" I closed my book to join the conversation? what's the difference between the two sentences?
You would 'join' a group of people, meaning to link up with, connect up with.
You could also be asked to 'come and join the conversation'.
'in' (as one meaning) expresses inclusion or involvement, so that 'join in' conveys the more emphatic welcome, of not just joining the group whose members are already engaged in conversation, but of feeling free to take an active part in the conversation.