The building of the dam was proposed by Sun-Yat Sen, who is the father of modern China, to protect the river communities from floods.
Answer:
Scientists use waves to study the different layers of the earth. Usually, they use seismic waves, which are waves generated by earthquakes or nuclear-test explosions. So, scientists study the path and speed of these waves through the earth to decipher boundaries and the materials that make up the layers.
Explanation:
