If you have the Primer and are working in improving your knowledge of Ecclesiastical Latin and you are alone, then this key is an absolute must. Like the Primer it is well produced and simply gives the correct answer to each of the exercises.
This is a useful accompaniment to Collin's Primer, especially if you get stuck on some of the more complex sentences or pieces. The only gripe I would have is that sometimes Dunlap translates things in a slightly different way than I would by following Collins and his method and the dictionary at the back. Occasionally it may change the sense of the sentence slightly, but as the Italians say "traduttore, traditore". If you are using it for reference it's fine, but if you want to directly quote it in order to give answers in a latin class you might have a problem or two.
Some might think it is a cheat to have a book which gives answers to any test, but if you are learning alone, where else do you go? So , as long as you at least attempt the tests in the Primer first, this is a useful book for anyone studying ecclesiastical Latin, in seminaries, but also elsewhere. .
This is superb, and a great help. I am a beginner as a student of Latin, and avoid frustration by looking up answers to questions I cannot work out myself. I feel edified and encouraged when I get simpler questions right first time. Many thanks to the author, J R Dunlap.