19.We’d better set off now, or it will be dark__________we know it.
We' ve published large quantities of books. This year___ we've published three million.
Why not look up the new word in a dictionary _____ you don’t know it ?
No one is allowed ____ the room in the daytime..
In the middle of the night, we ______signals for help from another ship.
Three hours with your girl friend _____to be a short time.