1.He is a doctor.
⇒ (phủ định) He isn't a doctor.
hoặc He is not a doctor.
⇒(nghi vấn) Is he a doctor?
2.That is a book.
⇒That isn't a book.
hoặc That is not a book.
⇒Is that a book?
3.These are my classmates.
⇒These aren't my classmates.
hoặc These are not my classmates.
⇒Are these your classmates?
#học tốt
#xin ctrlhn