All three sentences are asking about someone's thoughts, but they use different prepositions to convey slightly different meanings. Here are the differences: "What are you thinking?" - This sentence is asking about the person's current thoughts or ideas. It is an open-ended question that does not specify any particular topic or subject. "What are you thinking of?" - This sentence is asking about something specific that the person is thinking about. The preposition "of" implies that there is a particular object or subject in the person's mind that they are considering. "What are you thinking about?" - This sentence is similar to the second one, but it is more general. The preposition "about" implies that the person is thinking about a topic or subject more broadly, without necessarily focusing on a specific object or idea. In summary, the main difference between these sentences is the preposition used, which changes the meaning slightly. The first sentence is the most general, while the second and third sentences are more specific about what the person is thinking.

think of 和think about 我感觉same😂