have,building,each,look,first,they,in,enough,finish,but,much,at Do you know the differences between the new buildings and the old ones? Old buildings__brick(砖)and stone walls.The walls hold up the__. In cities,many modern buildings__as if they are made just of windows.Walls of dark glass reach high into the air.Many buildings are__than 50 stories(层) tall. Are walls of glass strong__to hold up the new buildings?No. The new glass walls do not hold up the bulidings,__they only cover up the frame(框架) made of steel.Have you ever watched a new building going up? The steel frame is built__. Then the gl-ass walls are hung on the frame.When the building is __, the frame does not show.The outside looks like windows without walls. The glass walls shine __ the sun with no decoration(装饰).Many people find __ beautiful just as they are.