'She's thinking about studying Law' = She isn't studying Law at the moment but is considering the possibility of enrolling on a course. This is present continuous used to talk about a process that's happening around the present moment. Further examples: I'm thinking about going for lunch, I'm hungry. She's thinking about quitting her job, she hates her boss! 'She (adverb of time e.g. often/never) thinks about studying law' describes a general behaviour that the person does often. This is the present simple, which we use to talk about routine, so we'd usually have an adverb of time in there too to indicate frequency. Further examples: She thinks about going on holiday from time to time, but can't really afford it. I think about calling Alex sometimes, but he never picks up the phone. Hope this is a bit clearer for you!

“She is thinking about studying law” is the usual way to say that she is not a law student yet but has been thinking (for a while) of becoming a law student. “She thinks about studying law” would be used less commonly. For example, if she thought for just a moment about studying law: “When she sees her financially successful friends, she thinks about studying law, but her real love is painting and so she quickly puts aside any thought of law school.” “What are you planning to do” and “What do you plan to do” are interchangeable.

Hello Marta, Actually the first one is better because it is an action in progress at/around the time of speaking. Best wishes Bob

Hello, Marta Do you want to express that something happens in general or that something is happening right now? In General = Simple Present Right now= Present Continuous I hope it helps! Source: https://www.ego4u.com/en/cram-up/grammar/simpre-prepro