Dave nearly ran into a block when walking down the street with his mind ______ on the word puzzle.
Before leaving home, make sure to turn off the electricity, lock the door, ______ the windows open.
I can _____ some noise while I’m studying, but I can’t stand very loud noise.
The idea for the new machine came to Mr. Baker ______ to his invention recently.
Professor Liu has ________ teach psychology since he came to the Central China Normal University.
----Any news about Bill Clinton? ----He left power three years ago and has a little now and a little then been ______.