29.1: B.

29.2: A.

29.3: D. 

29.4: C. 
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Ha Long Bay is one of Vietnam's most famous natural wonders. It is located in the northeast of the country, about 170 kilometers from Hanoi. The bay is known for its breathtaking limestone islands and emerald green waters. It covers an area of about 1.553 square kilometers and is home to nearly 2,000 small islands and islets. These islands come in many shapes such as lions or turtles.

One of the most special things about Ha Long Bay is its caves. Marry tourists enjoy exploring these caves, such as Sung Sot Cave and Thien Cung Cave, where they can see stunning rock formations. Another popular activity in Ha Long Bay is kayaking. Visitors can paddle between the islands and get close to the spectacular cliffs.

In 1994, Ha Long Bay was recognized as a UNESCO World Heritage Site. This recognition helps protect the area and promote tourism. Many visitors come to Ha Long Bay every year to enjoy the natural beauty and relax in the peaceful atmosphere. It is a place that shows the incredible beauty of nature in Vietnam, and it is definitely worth visiting.