1a. I am talking of Mohan.
1b. I am taking about Mohan.
2a. What did you think of his proposal?
2b. What did you think about his proposal?
3a. I’m thinking of doing something.
3b. I’m thinking about doing something.
4a. I’m thinking of going to the store, do you want anything?
4b. I’m thinking about going to the store, do you want anything?
Please correct all and comment.
Thanks.
All are possible.