When he saw all his books _____ here and there on the floor, he knew that something terrible _____.
A. lying; must have happened B. lie; must happen
C. lay; might have happened D. had lain; could have happen
When he saw all his books _____ here and there on the floor, he knew that something terrible _____.
A. lying; must have happened B. lie; must happen
C. lay; might have happened D. had lain; could have happen
A