Use arrows and key terms such as "red blood cells," "oxygen," and "EPO" to describe how high-altitude training helps athletes improve their performance at lower altitudes.

you go to account and hit delete!

explanation:

weathering - colorado river carves land in arizona to form the grand canyon. cracks form in a sandstone wall surrounding a house. a marble statue near the science museum is changing color due to rainfall

erosion - after a rainstorm, soil and rock piees litter the roadways. the sand dunes in the sahara desert are changing shape.

here's your answer.