공유 오디오

UNIT 6: WALKING AROUND (FLOORS & STAIRS) INTRODUCTION We walk on floors every day. We use stairs to go up and down. These are important parts of a building. They must be strong and safe. Ground Floors The ground floor is special. It is close to the earth. There are two common ways to build it. One way is a concrete slab. Workers prepare the ground, put a layer of hardcore (small stones), and then pour concrete on top. This makes a strong, solid floor. Another way is to build a suspended floor. T