-Would you like to help me clean the lab at 4 o'clock this afternoon?-I would like to, but I __________ listening practice then.
David was always ______ his best in any danger, but at that moment he froze.
As the spokeswoman said, ______ we should take action against them depends on what they will do.
In the reading room, we found her _______at the desk, with her attention ______on a book.
With more forests being destroyed, huge quantities of good earth _______each year.
The prisoner was released early because of good ____________.