1. Đại danh từ là từ dùng để thay thế cho danh từ: a. Không rõ nghĩa: Ví dụ: The boy cannot leave his father; for if he should leave him, he would die. b. Nghĩa được xác định: Ví dụ: The boy cannot leave his father; for if he should leave his father, his father would die.