Questions

In music, a fugue is a contrapuntal compositional technique in two or more voices, built on a subject that is introduced at the beginning in imitation and which recurs frequently in the course of the composition. 

Hence, the main theme of a fugue is called the subject.

Sport played on horseback is called as Polo. It is the national sport of Iran.

Settled agriculture was first seen in China around 6000 BC. The crops grown at this time were rice and millet.

Beginning in about 618 BC with classical millet agriculture, China's development of farming over the course of its history has played a key role in supporting the growth of what is now the largest population in the world.

Venus is known as earth's twin because of its closeness to the earth with respect to size, mass(weight) and density.