To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
Good for beginners or intermediate wanting to review grammar rules, this is a very formal structured exercise book style of learning. If you enjoyed doing homework you will like this. If you like something less formal, you may not. Great for those who do not have access to a class or teacher. You can write in the book, and check your answers in the back.