So the answer is: 90, 100,10,120; 120;
(2) As can be seen from the picture, in the book corner of Grade Three, there are the most books on science and technology and the least books on plants;
So, the answer is: technology, plants;
(3)( 1 10+85+ 105+ 120)÷4,
=420÷4,
= 105 (Ben),
A: On average, there are 105 books in each category.
(4) Let students take more books, plants with fewer books are placed in the corner, and others can be read according to the number of books in the picture.