A: Possibly. Many schools ban unsupervised access to answer keys because of past cheating. Ask your teacher if you can use it in class during a self-check station or if a parent can hold it at home.
Use the key wisely. Then, eventually, put it away. Have a specific workbook in mind (e.g., Glencoe’s Grammar and Language Workbook, Grade 9, ISBN 978-0028182940)? Mention it in the comments for edition-specific answer key guidance. Grammar Practice Workbook Grade 9 Answer Key Pdf
A: Many teacher’s editions have the answers printed in a colored overlay (often red). Use a red transparency sheet or simply photocopy the pages and use white-out to reveal answers gradually. A: Possibly