How did democrats hold power for so long in the 30s,40s, and 50s

Democrats held power for so long during the 30s, 40s, and 50s because the country entered the Great Depression. Democrats dominated this time period because its liberal policies and programs with FDR's "New Deal" were seen as the best way to combat the emergency bank closings.

Which of the following is not one of the major principles of ecology?\

first paragraph (and busy all the night ,with a silence deep and white )