article: This is Liu Fei's room. It's a small but nice room. On the wall, there are two maps. One is a map of China, the other is of the world. There's a desk in front of the window and on the desk there is a clock. Near the clock there is a glass. There's some water in it. And there are two pencils, one pen and some books on the desk too. There is a chair on the floor and under the chair there's a ball. Liu Fei often studies   in his room and he likes his room very much.
question: There are some books   _   .
options: on the chair on the desk on the floor on the wall