sentences: matter in the gas phase has variable volume & matter in the gas phase has variable shape ->  matter in gas phase has variable volume and shape  matter in gas phase has variable volume and shape & matter with variable volume and shape expands to fill the shape and size of its entire container ->  gas will expand to fill the shape of the container  gas will expand to fill the shape of the container & air is a kind of gas -> air will expand to fill the shape of the container