The natural rubber has been gathered from the sap of plants for centuries.
天然橡胶是几个世纪以来从植物汁液中收集来的。
2
Natural rubber has been gathered from the sap of plants for centuries.
从植物汁液中收集天然橡胶已经有几个世纪的历史。
3
The evolutionary purpose of rubber, and the reason why it has appeared independently in plants as diverse as trees, guayule and dandelions, is that it gums up the mouthparts of herbivorous insects.