| 摘要 |
<p>The bottom, beneath or near the water, is cleared of vegetation and a non-woven fabric is applied and fastened down. Pref. the fabric is of polyethylene terephthalate, or isotactic polypropylene, or polyamide, polyvinyl chloride, polyvinylidene chloride, cellulose acetate, poly acrylonitrile, can also be used. The material may have sand dumped on it.</p> |
