The Russians had turned to a Market system.
Because Cyanobacteria appeared
Cyanobacteria's excrement formed a lot of oxygen in the atmosphere which make the earth temperature cold
This allow a liquid water to formed on the surface ( because if the temperature is too high, the water will evaporate) and eventually formed oceans
Answer:
Scientists use waves to study the different layers of the earth. Usually, they use seismic waves, which are waves generated by earthquakes or nuclear-test explosions. So, scientists study the path and speed of these waves through the earth to decipher boundaries and the materials that make up the layers.
Explanation:
Answer:
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Explanation:
The Human Development Index (HDI) is a statistic composite index of life expectancy, education, and per capita income indicators, which are used to rank countries into four tiers of human development. A country scores a higher HDI when the lifespan is higher, the education level is higher, and the gross national income GNI (PPP) per capita is higher. It was developed by Pakistani economist Mahbub ul Haq and Indian economist Amartya Sen and was further used to measure a country's development by the United Nations Development Programme (UNDP)'s Human Development Report Office.