This study investigated how a person comprehends a subject-verb-object (SVO) sentence. In two experiments subjects comprehended sentences to form unitary representations in a sentence-picture verification task. Reference scope (superordinates or subordinates) and location of superordinates were manipulated. Both effects of reference scope and location of superordinates were obtained. These findings support a slot-filling model of sentence comprehension in which subjects successively create a slot for filling the previously integrated unit in comprehending a sentence. The slot-filling model should apply to comprehending English as well as Chinese sentences.