Âm thanh chia sẻ

A Real Project - The Small Bridge Last year, workers built a small bridge near my city. First, they dug big holes in the ground next to the river. Then, they put steel cages inside the holes. These steel cages are called rebar. Finally, they poured concrete into the holes. When the concrete got hard, it became the foundation. The bridge is strong because the foundation is strong. CONVERSATION 3: Pouring Concrete A site worker and an engineer are talking next to a concrete truck.  Worker: "Th