For example, activated carbon can be used in physical washing and it absorbs impurities, but on the other hand it is expensive to make pure activated carbon that isn't hazardous to the health. The processing of activated carbon could also be a waste of resources or harmful to the environment.
以活性炭為例，它有物理洗淨作用，會吸附髒東西；但從另一面來看，要製成純度很高、不會傷害人體的活性炭，需要花費很高的成本代價，處理活性炭的過程，也可能造成能源浪費或環境的污染問題。