Matter can be a solid, a liquid, or a gas. A solid,such as a rock, has from. It has its own shape. A liquid, such as water, has no shape of its own, but it can flow. A liquid can take the shape of any container into which it is poured. A gas, such as air, has no shape, either, but it can expand. When a gas is put into a closed container, it spreads out and fills the container.