Sure, I can help you with that. For the first part, here are the corrections: 1. We need to protect the environmental for the next generation. Correction: A -> D Revised sentence: We need to protect the environment for the next generation. 2. While her brother was in the army, Sarah writes to him twice a week. Correction: C -> wrote Revised sentence: While her brother was in the army, Sarah wrote to him twice a week. 3. Tommy left high school in the age of seventeen. Correction: C -> at Revised sentence: Tommy left high school at the age of seventeen. 4. It is my mom which does the cooking. Correction: A -> who Revised sentence: It is my mom who does the cooking. For the second part, here are the rewritten sentences: 1. After we listened to an introduction to the course, we asked some questions. Rewritten: Having listened to an introduction to the course, we asked some questions. 2. Our awareness campaign was a success. However, we still need to do more to stop cyberbullying. Rewritten using "Although": Although our awareness campaign was a success, we still need to do more to stop cyberbullying. 3. Tom and Jerry haven't talked to each other for 2 years. Rewritten: The last time they talked was 2 years ago. 4. Mr. Nam himself gave me this book yesterday. Rewritten: It was Mr. Nam himself who gave me this book yesterday. I hope these corrections and rewritten sentences are helpful! Let me know if you have any other questions or need further assistance with English writing exercises.