How could Dennis distinguish between a book and a pillow of the same size and at an equal distance in front of him A book would produce ______.

单项选择题The writer says that a blind baby is doubly handicapped in comparison to a sighted child because ______.

单项选择题If someone holds a book 6 feet directly in front of Denis and then moves it only 1 foot directly in from of him, what change in sound does Dennis hear

单项选择题Bower believed Dennis would be the ideal subject for his experiment because ______.

单项选择题The reason why the author says in the essay that the title of the movie This Land Is Mine is ironical was that the land is ______.

单项选择题That year in New Jersey lives in my mind... ,as the author intended, means ______.