问题
选择题
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
答案
答案：A
考查感官动词和情态动词。see sb./sth. doing sth.看到某物/某人正在做某事；books和lie是主动关系，故用lying；must have done“一定做了某事”，表示肯定的推测。故选A。