Should the celebration of Zheng He replace the celebration of Christopher Columbus?

What causes the cyclical changes in the appearance of the moon?

17. the soil erosion pictured here is the result of what? a. harvesting renewable resources at a rate greater than the sustainable yield b. a mudslide caused by excessive rains c. harvesting renewable resources at a rate lower than the sustainable yield d. the transition between geologic eras and eons

At which boundary does subduction stop occurring, resulting in a mountain range?