Answer Key to the relevant course. Focus on Grammar, Second Edition, is a four-level grammar series written by practicing professionals. The series focuses on English grammar through lively listening, speaking, reading, and writing activities. In order to learn the formal rules of a language, students need to practice new structures in a variety of contexts to help them internalize and master them. To This end, Focus On Grammar provides an abundance of both controlled and communicative exercises so students can bridge the gap between knowing grammatical structures and using them. The many communicative activities in each unit enable students to personalize what they have learned.