A．By comparing it to similar devices used 1,000 years later.
B．By using a kind of rays to see inside of the mechanism.
C．By referring to ancient Greek writings about the mechanism.
D．By consulting with colleagues in the field of physics.

A．To point that the Botai people sometimes did not have enough food.
B．To compare the physical features of domesticated and wild horse.
C．To prove that the horses of the Botai people were domesticated.
D．To emphasize that horse milk was popular in some ancient societies.

A．They do not reveal information about horse domestication.
B．They are very different from the bones of modem horses.
C．They date to the period when the Botai people had become moving about.
D．They suggested that horses were first domesticated by another ancient people.