Superted,
The full explanations of these questions, together with more than 1000 others, are contained in a book that I have produced. Unfortunately direct advertising in these posts is not permitted.
My purpose in asking memebers to e-mail me is simply to enable me to offer the book for sale. It is more effective to make the offer to people who are studying for these exams, rather than simply sending e-mails to all members. Anyone receiving my offer is of course free to decline it. Receiving the answers to these questions is not conditional upon buying anything.
As I have already offered you the book and you have not responded, I will send you the answers by e-mail.
The second reason for not posting the answers directly in this forum is that the whole text is rather long. You can see from my previous posts just how long twenty questions are when posted in this forum. Each of the answers is about three times as long as the related question. The pprune system is often already tediously slow without my adding to this problem.