Read the passage and decide whether the statements are TRUE (T), FALSE (F) or DOESN'T SAY (NI).

SƠN ĐOÒNG CAVE

Sơn Đoòng Cave is located in the limestone mountains of the UNESCO-listed Phong Nha – Kẻ Bàng National Park. It was first discovered in 1991 by a local man and became internationally famous in 2009 when a group of scientists from British Cave Research Association explored it.

Sơn Đoòng Cave was created from 2 to 5 million years ago while a river flowed through the limestone mountain area. The water eroded the limestone and created long underground tunnels. The cave is over 200m high, 200 m wide and at least 9 km long. Sơn Đoòng Cave consists of two entrances, which is unique among other explored caves in Phong Nha - Kẻ Bàng National Park. Having explored the cave, the scientists were surprised at the spectacular scenery of numerous columns of more than 70 meters high. Sơn Đoòng Cave is the largest cave passage in the world. International explorers were amazed to see that this fascinating cave system has its very own rainforests. Deep inside the cave exists a tropical jungle named “Garden of Eden" by the explorers. This is where unique species of plants and trees can be found. Also, the cave has a 2.5-kilometer underground river. Not far from the “Garden of Eden” lies an enormous “pearl collection” consisting of thousands of small rare limestone cave pearls in dried ponds, making it an incredible feature of the cave.

Sơn Đoòng Cave was opened to the public in 2013. A local adventure tour company Oxalis has been taking a limited number of tourists per year on four-day expeditions into Sơn Đoòng Cave since then.

Read the passage and decide whether the statements are TRUE (T), FALSE (F) or DOESN'T SAY (NI).SƠN Đ...