Completar Frases The origin of plasticsVersión en línea Technologies for spanish speakers por Miriam Cano Cano 1 coal Synthetic origin carbon Natural monomers polymer synthetic petroleum chemical resins raw Plastics are materials made up of long molecules ( ) which are a combination of and hydrogen atoms . A set of many monomers forms a . Depending on their they can be : . - plastics , obtained directly from materials found in nature , such as rubber or . . - plastics made by processes from raw materials as , and natural gas . Most of plastics we use are .
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