—Someone is knocking at the door. Who ______ it be? —It ______ be Tom. He is still in the school.

Let’s discuss the problem after school.

When I opened the fridge, there ______ only some eggs and a bottle of milk.

My brother used to _______ up late, but now he is used to _______ up early.

—What is your sister doing ,Tom?—She      at the mall. She    every Sunday.