The scientist knew nothing about the matter, because he was always ______ himself in his study.
A modern city has been set up in_______was wasteland ten years ago.
It has been a long time for human to make _____ to reach the moon.
—Hi, Tom. Any idea where Jane is? —She_______in the classroom. I saw her there just now.
The boy_______on the ground_______that he_______the book on the table.
You must apologize_______your mother_______your rudeness.