Mr. Zhang put the four treasures of the study in a cabinet with four drawers, and asked the students to guess which floor the pen, ink, paper and inkstone were on. According to the order of pen, ink, paper and inkstone, Xiao Li guessed that the four treasures were installed on the first, second, third and fourth floors, Xiao Wang guessed that the four treasures were installed on the first, third, fourth and second floors, and Xiao Zhao guessed that the four treasures were installed on the fourth, third, first and second floors, Xiao Yang guessed that the four treasures were installed on the fourth, second, third and first floors in turn. Mr. Zhang said that Xiao Zhao didn't guess right, Xiao Li and Xiao Wang guessed right one, and Xiao Yang guessed right two.
 The third drawer is not filled with inkstone can be inferred.