3. Point out the subject of the sentence and state what it is expressed by. Example: He likes oranges. – He is a subject which is expressed by personal pronoun. 1. People are always rather bored with their parents. That’s human nature. 2. “I have nothing to declare except my genius.” (O. Wilde at the New York Customs House) 3. Which way has Nick gone? 4. To do nothing is the way to be nothing. 5. Something is rotten in the state of Denmark. 6. The young in spirit enjoy life. 7. To be seventy years young is sometimes far more hopeful than to be forty years old. 8. Well begun is half done. 9. One should eat to live, not live to eat. 10. Two is company, but three is none. 11. What is the matter with him? 12. Here lies my wife: here let her lie. Now she’s at rest, and so am I. (epitaph intended for J. Dryden’s life). 13. The grocer’s was closed. 14. For us to e left by ourselves was a rare happening. 15. ‘Be’ is a verb.

For the first part of your question, the "are you not"/"is he not" isn't more emphatic, it is much more formal. If you were speaking and wanted to make the sentence more emphatic, you'd put the emphasis on the verb: "You ARE stupid, aren't you?" "He IS stubborn, isn't he?" However, for the second part of your question, using the full words to answer a question or to deny a statement is definitely more emphatic. This is particularly true for questions that are statements, asking you to agree or disagree, like your examples above.