What symbol did the maya use for zero? what symbols did they use for one and for five?

According to documents in wiesner et al., why has access to water been such an important factor in the rise of complex societies? how did ancient societies address the problems associated with harnessing these powerful resources? how have historians assessed and addressed this issue? cite the appropriate documents relevant to the response.

Will have the greatest effect on human health. pollution in the a. troposphere b. stratosphere mesosphere d. thermosphere

Describe some effects of the rise of communism in the soviet union?