The text is for the following question.

My Room

My favorite place in my house is my bedroom. I painted it pink because it's my favorite color. I put pictures of natural scenery on the wall.

Near the window is my desk. There is an alarm clock, a dictionary, and some encyclopedias on the desk. The alarm clock wakes me up in the morning. The dictionary and the encyclopedias help me when I study. My bed is very comfortable. The color of the sheet is pink. The pillows and the bolsters are pink, too.

When does the writer use the encyclopedias?