Complete Advanced Self-Study Pack

This book immediately starts with a ridiculous difficult exercise without providing a concrete lesson to learn. It seems to me the author just wants a non-native English speaker to just fail. It sends the message "You know nothing, John Snow!" Great! I knew before that I am not a non-native speaker - that is why I do a course - which uses this book. The book provides answers to the exercises. However, some answers in the book do not even make sense to the teacher - a native English speaker. How can that be? The more I use the book, the more I get the feeling the people who wrote the book have no pedagogic understanding.