__________ has the right mixture of oxygen and carbondioxide for animals and plants.

The earth is made up of both land and ___________.

The line at which the earth and the sky seems to meet is called the ________.

The sun is also a ___________.

One fourth of earth's surface is _________.

The solar system is a family of _______ planets.

Which is the layer of air that surrounds the earth?

__________ has both air and water which living being needs to live.

The word planet is derived from a _________ word.

In early days,people thought that the shape of earth was ____________.