What property of a wave changes to create the doppler effect?

speed

amplitude

medium

frequency

wait history, who want to talk about history, boring.

the correct statement is letter a.   according to the mandate of heaven, kings were considered godlike beings, so they could do as they .

the mandate of heaven is a chinese political and religious ideology used since ancient times to justify the rule of the king or emperor of china, that has been in place since the zhou until the dynasty system ended. it has been created to justify the zhou as the main power of the region. in order to keep harmony, the ruler has to make what he wants and what people want. he had to make good choices to satisfy the people and then they will be happy and keep you in power.

i think it’s a i hope that right : )

the correct answwer is d