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1. I did ask him not to tell her the truth, but he told her everything.
2. How did it happen that he failed at the examination? He did know the subject well.
3. You won't beleive me, but I do want to become a doctor.
4. Do read the book, it is well worth reading.
5. He said he would give up smoking and he did give it up.
6. Do stop arguing.