Answer:
1.) Tigers are one of the most protected animal species in the world
2.) Bangkok, London, Paris and Singapore the the most visited cities in the world in 2013.
3.)Supercalifragilisticexpialidocious is one of the least used words in the dictionary
4.) Antarctica is least explored continent in the world ; the icebergs, wind and subzero temperature makes it impossible to live there permanently.
5.)Namibia is the most populated country in Africa; 2 million people live in an area of 800,000 km²
6.)In my opinion, monkeys are the most interesting animals that exist.
Explanation:
The question requires that ; For each statement, the missing gap is filled with either least or most based on which best fits the sentence in terms of opinion or meaning.