Trade involves the transfer of goods or services from one person or entity to another, often in exchange for money. A system or network that allows trade is called a market.
The product of mental labor — science — always stands far below its value, because the labor-time necessary to reproduce it has no relation at all to the labor-time required for its original production.
Karl Marx Addenda, "Relative and Absolute Surplus Value" in Economic Manuscripts (1861–63).
One of the most important questions posed by climate change is whether species can respond to a changing climate quickly enough to avoid extinction. In order to survive, populations must either be able to adapt to or tolerate the change in environment, or migrate to more suitable conditions.
EN 
CS
DE
ES
FR
HU
IT
PL
PT
РУ
SK
TR
УК
AR
中文
