공유 오디오

UNIT 3: MAKING THE BUILDING STRONG (WALLS & MASONRY) INTRODUCTION After the frame, we build the walls. Walls do many things. They keep the weather out. They make rooms private. And they can also help hold the building up. STORY 1: Bricks and Blocks Many walls are made from bricks or concrete blocks. Bricks are small and made from clay. They are baked in a very hot oven. Concrete blocks are bigger. They are made from concrete. Workers stack the bricks or blocks in rows. They use mortar between th