Explanation

• The longest railway tunnel in the world is the Gotthard base tunnel.
• The Gotthard base tunnel is situated in Switzerland.
• Gotthard base tunnel is 57 Km long and provides high-speed rail link.
• Seikan Tunnel is 53 Km long and situated in Japan.
• Yulhyeon Tunnel is 50 Km long and situated in South Korea.
• Channel Tunnel is situated on the English Channel on Dover strait.

Explanation

• The largest undersea railway tunnel is constructed between France & England
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• The largest undersea railway tunnel constructed between France & England is the Channel Tunnel 
  
• This tunnel was built in 1988.
• The length of this tunnel is 31.4 Miles.
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• The project to build the undersea leg between England and France began in earnest in 1986.
• But as work progressed, the owner, Eurotunnel, and the Anglo-French consortium responsible for the design and construction
  

Explanation

Pakistan has signed and ratified the United Nations Convention on:

Combating Desertification and Drought (singed in 1994 and ratified it in 1997)

The International Convention on Climate Change ( singed in June 1992 and ratified it in June 1994)

The International Labour Convention on Child Labour. (ratified on October 11, 2001)

Explanation

Explanation

China has successfully completed the construction of the Tianshan Shengli Tunnel, which is now recognized as the world's longest Expressway Tunnel. 

The Tianshan Shengli Tunnel holds the record as the longest expressway in the world, stretching over 300 kilometers. 

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Explanation

The Channel Tunnel is an undersea tunnel linking southern England and northern France. It is operated by the company Getlink.