| 1 | Today, we study the second unit of the book. | |
| 2 | This textbook has twenty units. | |
| 3 | In this Unit, we will review and practice those sounds as well as contrasting them with three others: . | |
| 4 | The kilometer is the biggest unit of length in the metric system. | |
| 5 | Popular site features include an integrated video-chat-application, writing exercises that can be corrected by native speakers, review quizzes, and learning units. |
