Dear Alan,
I would like to compliment you on the interactive tests, once I had started I was unable to to stop until I had completed them all. It was really informative and a pleasure as well as a challenge to do the advanced tests.
I would just like to know if you would be interested in finding out about a few mistakes I came across (10 to 12.) Please let me know and I will point them out to you.
Have a great day.
Beate