Động từ tobe (am/is/are, was/were) dùng thay thế
Chúng ta có thể dùng am/is/are hoặc was/were để thay thế cho cả cụm từ đã nói trước đó, tránh lặp lại.
- She isn't tired, but he is. (= he is tired)
- "Are you tired?" - "I was, but I'm not now." (= I was tired)
Không được dùng dạng rút gọn 'm/'s ở cuối câu:
- ✓ She isn't tired, but he is.
- ✗ She isn't tired, but he's.
Nhưng có thể dùng dạng phủ định rút gọn isn't/wasn't/aren't/weren't:
- "Are you and Jane working tomorrow?" - "I am, but Jane isn't."
Sau Yes/No:
- "Are you tired?" - "Yes, I am. / No, I'm not."
- "Is there a bus to the airport?" - "Yes, there is. / No, there isn't."