I think i will go to the park means you are more likely than not to go to the park, but there is still a possibility you won't go to the park. 1.i think it's cool when people recognize me. I won't be volunteering for that detail, i don't think (in other words, let some other.
I think you are right on. This is also used as part of an idiomatic expression. (what do you think my emotional reaction was?).
I'm wondering if there's any difference between the use of i think and i think that in a verb+adj.+when sentence. As edwin ashworth mentioned in a. You can use if in this way with know, as in i don't know if this works, but it doesn't work with think. This rhetorical question is inviting empathy or sympathy, especially after something bad, for.
I've also met have heard of/about something. 2 think about it is the most common according to this ngram, but both think it over and think on it mean essentially the same thing. The example with if in do you think if this this car works is not grammatical. It's rather a conversational filler, making the question appear less stark (ie having a pragmatic role).
The 'do you think' hardly adds any semantic content; As for your second question, i don't think it's confined to disappointment. consider: Think about means to ponder or consider. If the full sentence was how do you think it makes me feel? then it could make perfect sense, and would be the same in meaning.
Is there a difference between think of something and think about something? How do you think i felt? I think i heard how do you think.?