13. He was absorbed ____ a book and didn’t hear your repeated call.
I looked everywhere in the house ______ a key that had been lost.
The man is standing _______ his back _______ the fire.
I don’t want to _______ money on such books.
He had ______ in finding Mr. Green’s house.
——Who telephoned just now? ——Sorry. I couldn’t ______ the voice.