In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: BACKGROUND : The most striking of carboplatin ' s advantages ( CBDCA ) over cisplatin ( CDDP ) is its markedly reduced rate of neurotoxic effects .
### Output Text:
BACKGROUND : The most striking of <span class="chemical">carboplatin</span> ' s advantages ( <span class="chemical">CBDCA</span> ) over <span class="chemical">cisplatin</span> ( <span class="chemical">CDDP</span> ) is its markedly reduced rate of neurotoxic effects . 