With all his attention ____ on the computer game, the boy even didn't notice his mother came in.
While he was at____ college, he took part in political activities, and was soon throw into ____ prison.
I was in the baths , ______ I didn’t hear the telephone, which was ringing several times.
She was so _____ in her job that she didn’t hear anybody knocking at the door.
Our professor told us that salt water _____ at a lower temperature than fresh water.
Until recently historians assumed that calendars ________ with the advent of agriculture.