Is earth a totally open system true or false

The government of country a has determined there is a coal shortage a seed on mining reports as a result of these data the government decreases coal exports to other nations access to information country a

This word for a bug or malfunction was popularized in the 1962 book into orbit by the mercury astronauts

People keep spending additional units of a particular resource on a want until their marginal benefit is  decreasing withgreater thanless thannot affected by  their marginal cost.