Based on the previous studies, this article tried to explore the extent to which the effects of comprehension monitoring adjunct questions and feedback facilitating reading comprehension.

The research concerned indicates that adjunct question can facilitate reading comprehension; that type,frequency and position of question affect the effects of adjuncttion, and that the mechanism of adjunct question can be interpreted by directed - attention model and informationprocessing model.

, concepts of null value, incomplete tree tuple are proposed, based on it, the definition of weak functional dependency and its satisfaction are given; second, the additivity problem for weak functional dependencies are researched, an algorithm that decide whether a given set of functional dependencies is weakly sati.