第 12 单元 - 参考

A bridge is a structure built to cross over a gap, such as a river, road, or valley, allowing people, vehicles, or animals to cross from one side to the other. Bridges are made from materials like wood, steel, concrete, or stone and come in various designs, such as arch, beam, or suspension. They can range in size from small footbridges to large, multi-lane highway bridges. Bridges are important for transportation, connecting different areas and making travel easier and safer. They are also often considered engineering landmarks.

Geography is the study of the Earth’s physical features, climate, and the spatial relationships between places. It explores how natural and human-made features shape landscapes, environments, and human activities. Geography helps us understand the distribution of populations, resources, and the impact of human actions on the planet.

A tunnel is an underground passage that is typically built for transportation, such as roads, trains, or utilities. It can also be used for water flow or as a way to bypass natural obstacles like mountains or rivers. Tunnels are usually dug or drilled through the earth or rock, and they can vary in length, width, and purpose. They are often lined with concrete or steel to prevent collapse. Tunnels are an essential part of infrastructure, providing safe and efficient routes for people and goods. Some tunnels are open to the public, while others are used only for specific purposes, like mining or utilities.