| 摘要 |
<p>A swimming pool cover (1) which has a density greater than that of water and which comprises buoyancy chambers (2) which can be filled with air to render the cover (1) buoyant so that it will floaton the surface of a pool and from which the air can be exhausted or expelled so as to cause the cover (1) to sink to the bottom of a swimming pool when the swimming pool is required for swimming. </p> |
