—Look at the boy running on the ground. Is it Davis?—It ______ be him. I saw him go to the teacher’s office just now.

—You look so tired. —Yes. The loud noise upstairs stopped me        the whole night.

 ---Must I be back home before 6 o’clock? ---No, you ____. But don’t be too late.

—Is that man Mr Hu?—That ______ be Mr Hu. Because he has gone to Japan with his wife.

In ancient times, dogs were mainly ______helping people hunt( 打猎) .Now they are more useful-they can help the blinds, search for the bad eggs,...