Give short "yes" or "no" answers to the following questions.

1. Did Euclid bring together all the geometrical laws known at that time?
    Yes    No   
2. Did Pythagor write the book "Pythagor's Elements of Geometry"?
    Yes    No   
3. Are certain prepositions proven and deduced in any deductive system?
    Yes    No   
4. We must get started to proof by assuming some theorems, mustn't we?
    Yes    No   
5. Is modern mathematics the same as in the times of Euclid?
    Yes    No   
6. Did Euclid wrongly consider that the postulates and definitions are absolutely certain self-evident truths?
    Yes    No