This is ____ book I bought yesterday. Isn't it _____useful one?
You will fail the exam _____ you study harder than before.
Peter’s teacher was very happy because he made the _____ mistakes in this exam.
Our classroom is on the _____ floor. We can hear the students singing on the fourth floor.
People like eating _____ very much. They are called “apples under the ground”.
The Xisha Islands are _____ South China Sea. They belong to China.