The Easter Island<span> statues, or moai, are enormous stone figures placed along the coastline as if surveying the island's interior lands. One of archaeology's greatest mysteries is what </span>happened to the Rapa Nui<span> of </span>Easter Island<span>. ... For centuries, observers believed that the </span>Rapa Nui<span> suffered a catastrophic population crash.</span>
'The Four Great Inventions of Ancient China' refers to paper, gunpowder, printing, and the compass. These four great inventions greatly promoted the development of China's economy, politics, and culture.
The experimental factor that is manipulated by an investigator is called the independent variable, while the factor that may be manipulated by the influenced experimental treatment is called dependent factor. Experimental factors are general type or category of treatments. Different treatments constitute different levels of a factor.
