I also don't understand what the example sentences are for, but I can try to explain the difference between those words. A person's "mind" is just our awareness of the world. It is essentially our brain. It is what happens inside our heads. "Thought" is both the noun form of the verb "think" and also the past tense. A thought is something that you think in your mind. If it is in the past, you didn't "thinked" (this is not a word), you "thought". An "idea" is a type of thought that leads to action. It is usually used when there is a problem you are trying to solve, and you have a thought that could solve it. Examples: "In my mind, zebras are black with white stripes." "Describe the house to me so I can picture it in my mind." "I thought zebras were black with white stripes, but today I learned they are white with black stripes!" - Here, "thought" is a past tense verb. "What are your thoughts?" - Here, "thoughts" is a plural noun. Someone is asking someone else what they think about something. "I have an idea on how I can make more money." - In this case, the idea isn't solving a problem directly, but it is a thought that leads to an action. "The lid of the jar was stuck, but I had the idea of running it under warm water to loosen it."

I'm not sure I understand your question. In fact I don't... How and why do you need to use these three words? Do you mean one in each sentence??? 1 is an 'intention' 2 and 3 are 'opinions'

As another suggested the three words are certainly different but can be used in similar ways at times. Examples: I like the idea of having a cup of coffee now. (perhaps used as a response to someone asking if you want a cup of coffee as well since they are having one.) I thought I would have a cup of coffee. -- Basically the same meaning as your first statement. The idea that English pronunciation is difficult is (correct/a really silly claim/is very true for some people....) To my mind, English pronunciation is difficult. (pretty much the same as "I think" ) Taking this train would be a better idea. Each of the above is generally the same as your statements and would be understood but will have some nuances that might carry some subtle differences in the tone. For example, saying "I think...." is certainly expressing your thought but also (for me at least) implies something of a general view -- the speaker implies that others should think that as well. "To my mind...." is really saying something like "To my way of thinking...." which then allows the interpretation that the speak is really speaking about how something is for that person in particular but allows things to be different for others. This difference might be important when disagreeing with someone about something that is not an empirical fact.

Brain is our physical organ where mind occurs. Mind is that space/place in our brain that gets activated when the brain is in action: neurological connections occurring that we experience as memories, thoughts, perceptions, etc. As said above, Thought is one of the manifestations we experience in the mind. Idea is a conscious thought that could lead to action... and idea is a spark of inspiration that we experience in the mind ... who initiates the spark is a whole different mystery. There is also awareness, which is what we experience when we take the seat of the observer and stop feeling identified with all the activity that is going on in the mind (all that chatting that is going on there) ... when you experience awareness, you see things more clearly, not biased by the perceptions of your mind.

This is a good question. "Mind" is sometimes interchanged with "brain", but the brain is a physical organ, and the "mind" is the invisible **you** that occupies the brain. You could also say that the mind is the place inside of you where all of your thoughts and feelings happen. Some people think that the mind and the soul are the same, but some people disagree with this idea. (By the way, we also use the word "mind" in a different way, when you wan to say that something doesn't bother you, you can say "I don't mind.") Ok, now "idea" and "thought" are closely related. Every idea is a thought, but NOT every thought is an idea. An idea is something like imagining a new design for a car, or a new melody fort a song, or the perfect gift for your boss. In those cases, you could say "I have an idea..." A thought can be as mundane as "I am hungry." or "My foot hurts." or "I like this book." It is the dialogue (or monologue) inside of your head. So "ideas" begin as thoughts, but many "thoughts" are just mental chatter that don't qualify as ideas. This is a very good question. Trying to understand these concepts in a different language is not easy. Good work and good luck!