.Operation rooms should be kept free ______ bacteria of any kind.
This book _______twelve units, ______two mainly revisions.
--Why does the lake smell terrible?--Because large quantities of water _______.
I hope, first of all, that we shall never lose _____ heart in face of _____ failure.
--Now, where is my purse?--______! We'll be late for the picnic.
--- The manager of the factory wants to improve production a great deal, but he doesn’t spend much on technology.---I am afraid he won’t realize his dream. You know ________.