TeacherMolly老师陪娃刷题第425篇哦！
In November 2023, the main line of the 24-km-long Shenzhen-Zhongshan Link, which includes bridges, islands, tunnels, was fully connected. One part of it, the cross-sea tunnel, is around 6.8 kilometres long and is the world's longest and widest steel shell concrete underwater immersed tube (钢壳混凝土沉管) tunnel.
Do you know how the tunnel was built? The first step was to produce the tunnel parts in factories. The parts were made from concrete and steel. To make sure the parts were protected from seawater erosion (侵蚀), they were coated with special layers. After production, they were transported from factories into the ocean. They were filled with air so that they could stay above the water. After they were moved to the right place, engineers opened the ballast water tanks (压载水箱) inside them to let water in. In this way, they could sink to the bottom of the sea.
After all parts had been placed correctly, engineers connected the joints (连接处) of every proof tube with waterproof rubber material to prevent water from getting in. The joints of the tunnel were covered with gravel to make the environment still suitable for local sea creatures. Finally, workers paved roads inside the tunnel, making it ready for use.
The record-breaking length and the weight of parts created great challenges when placing and connecting them. So how did the engineers make sure each part was connected in the right way? The answer lies in BeiDou satellite positioning. With its help, installation accuracy (安装精度) could be controlled down to the millimeter level.
The Shenzhen-Zhongshan Link has been open to traffic since June, 2024. The travel time between Shenzhen and Zhongshan is reduced from two hours to about 30 minutes, reported Xinhua.
题目
( )1. What does the underlined word "they" in paragraph 2 refer to?
A. The factories.
B. The bridges.
C. The tunnel parts.
D. The engineers.
( )2. Why was the tunnel covered with gravel after all the tunnel parts were joined?
A. To make the tunnel hard to be shaken by earthquakes.
B. To avoid the tunnel parts being broken by the sea water.
C. To make the environment still good for local sea creatures.
D. To decrease the destruction and pollution of our environment.
( )3. How did the engineers make sure each part was connected in the right way?
A. The engineers used special machines to make sure the connection.
B. BeiDou satellite positioning helped make sure the installation accuracy.
C. All parts could sink to the bottom of the sea by opening the ballast water tanks.
D. Each part was coated with special layers to protect them from seawater erosion.
( )4. Which of the following is TRUE according to the passage?
A. The Shenzhen-Zhongshan Link is around 6.8 kilometres long.
B. The tunnel parts were made from concrete and steel in factories.
C. The rubber material between joints is used to prevent air from getting in.
D. People could travel between Shenzhen and Zhongshan within an hour in June 2023.
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