—Must I return the book tomorrow?—No, you ________.You can keep it for three days.

We should spend as much time as we _______ over our lessons.

— I am going to the dentist at 4 o'clock and it is 3：30 now.— Well, if you ______ leave earlier today, please ask the director for permission.

He _______ have completed his work；otherwise, he wouldn’t be enjoying himself by the seaside.

 ______ Tom be in his office so late at night ?